diff --git a/packages/NodeTypeResolver/src/StaticTypeToStringResolver.php b/packages/NodeTypeResolver/src/StaticTypeToStringResolver.php
index 90e791f75137..a0ab69f392e9 100644
--- a/packages/NodeTypeResolver/src/StaticTypeToStringResolver.php
+++ b/packages/NodeTypeResolver/src/StaticTypeToStringResolver.php
@@ -10,6 +10,7 @@
 use PHPStan\Type\FloatType;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\MixedType;
 use PHPStan\Type\NullType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
@@ -36,6 +37,7 @@ public function __construct(CallableCollectorPopulator $callableCollectorPopulat
             BooleanType::class => ['bool'],
             StringType::class => ['string'],
             NullType::class => ['null'],
+            MixedType::class => ['mixed'],
 
             // more complex callables
             function (ArrayType $arrayType): array {
@@ -69,8 +71,7 @@ function (IntersectionType $intersectionType): array {
                 return $this->removeGenericArrayTypeIfThereIsSpecificArrayType($types);
             },
             function (ObjectType $objectType): array {
-                // the must be absolute, since we have no other way to check absolute/local path
-                return ['\\' . $objectType->getClassName()];
+                return [$objectType->getClassName()];
             },
         ];
 
diff --git a/packages/TypeDeclaration/src/PhpDocParser/ParamPhpDocNodeFactory.php b/packages/TypeDeclaration/src/PhpDocParser/ParamPhpDocNodeFactory.php
index 0d2de5ef4f78..2799bf0047bd 100644
--- a/packages/TypeDeclaration/src/PhpDocParser/ParamPhpDocNodeFactory.php
+++ b/packages/TypeDeclaration/src/PhpDocParser/ParamPhpDocNodeFactory.php
@@ -31,12 +31,12 @@ public function create(array $types, Param $param): AttributeAwarePhpDocTagNode
         if (count($types) > 1) {
             $unionedTypes = [];
             foreach ($types as $type) {
-                $unionedTypes[] = new IdentifierTypeNode($type);
+                $unionedTypes[] = $this->createIdentifierTypeNode($type);
             }
 
             $typeNode = new UnionTypeNode($unionedTypes);
         } elseif (count($types) === 1) {
-            $typeNode = new IdentifierTypeNode($types[0]);
+            $typeNode = $this->createIdentifierTypeNode($types[0]);
         } else {
             throw new ShouldNotHappenException(__METHOD__ . '() on line ' . __LINE__);
         }
@@ -53,4 +53,14 @@ public function create(array $types, Param $param): AttributeAwarePhpDocTagNode
 
         return new AttributeAwarePhpDocTagNode('@param', $paramTagValueNode);
     }
+
+    private function createIdentifierTypeNode(string $type): IdentifierTypeNode
+    {
+        if (class_exists($type)) {
+            // FQN class name
+            $type = '\\' . $type;
+        }
+
+        return new IdentifierTypeNode($type);
+    }
 }
diff --git a/packages/TypeDeclaration/src/Rector/ClassMethod/AddArrayParamDocTypeRector.php b/packages/TypeDeclaration/src/Rector/ClassMethod/AddArrayParamDocTypeRector.php
index cc085825cd4c..36c47b627810 100644
--- a/packages/TypeDeclaration/src/Rector/ClassMethod/AddArrayParamDocTypeRector.php
+++ b/packages/TypeDeclaration/src/Rector/ClassMethod/AddArrayParamDocTypeRector.php
@@ -99,14 +99,11 @@ public function getNodeTypes(): array
      */
     public function refactor(Node $node): ?Node
     {
-        /** @var Param[] $params */
-        $params = (array) $node->params;
-
-        if (count($params) === 0) {
+        if (count($node->getParams()) === 0) {
             return null;
         }
 
-        foreach ($params as $param) {
+        foreach ($node->getParams() as $param) {
             if ($this->shouldSkipParam($param)) {
                 return null;
             }
@@ -116,7 +113,8 @@ public function refactor(Node $node): ?Node
                 return null;
             }
 
-            $this->docBlockManipulator->addTag($node, $this->paramPhpDocNodeFactory->create($types, $param));
+            $paramTagNode = $this->paramPhpDocNodeFactory->create($types, $param);
+            $this->docBlockManipulator->addTag($node, $paramTagNode);
         }
 
         return $node;
diff --git a/packages/TypeDeclaration/src/Rector/Closure/AddClosureReturnTypeRector.php b/packages/TypeDeclaration/src/Rector/Closure/AddClosureReturnTypeRector.php
index 34c7686ffa3e..9cb7c3aec344 100644
--- a/packages/TypeDeclaration/src/Rector/Closure/AddClosureReturnTypeRector.php
+++ b/packages/TypeDeclaration/src/Rector/Closure/AddClosureReturnTypeRector.php
@@ -90,8 +90,8 @@ public function refactor(Node $node): ?Node
         }
 
         $inferedReturnTypes = $this->returnTypeInferer->inferFunctionLike($node);
-        $returnTypeInfo = new ReturnTypeInfo($inferedReturnTypes, $this->typeAnalyzer, $inferedReturnTypes);
 
+        $returnTypeInfo = new ReturnTypeInfo($inferedReturnTypes, $this->typeAnalyzer, $inferedReturnTypes);
         $returnTypeNode = $returnTypeInfo->getFqnTypeNode();
         if ($returnTypeNode === null) {
             return null;
diff --git a/packages/TypeDeclaration/src/Rector/FunctionLike/AbstractTypeDeclarationRector.php b/packages/TypeDeclaration/src/Rector/FunctionLike/AbstractTypeDeclarationRector.php
index fdaa50303471..1187a30abeb8 100644
--- a/packages/TypeDeclaration/src/Rector/FunctionLike/AbstractTypeDeclarationRector.php
+++ b/packages/TypeDeclaration/src/Rector/FunctionLike/AbstractTypeDeclarationRector.php
@@ -128,7 +128,7 @@ protected function isChangeVendorLockedIn(ClassMethod $classMethod, int $paramPo
      * @param Name|NullableType|Identifier $possibleSubtype
      * @param Name|NullableType|Identifier $type
      */
-    protected function isSubtypeOf(Node $possibleSubtype, Node $type, string $kind): bool
+    protected function isSubtypeOf(Node $possibleSubtype, Node $type): bool
     {
         $type = $type instanceof NullableType ? $type->type : $type;
 
@@ -139,17 +139,8 @@ protected function isSubtypeOf(Node $possibleSubtype, Node $type, string $kind):
         $possibleSubtype = $possibleSubtype->toString();
         $type = $type->toString();
 
-        if ($kind === 'return') {
-            if ($this->isAtLeastPhpVersion('7.4')) {
-                // @see https://wiki.php.net/rfc/covariant-returns-and-contravariant-parameters
-                if (is_a($possibleSubtype, $type, true)) {
-                    return true;
-                }
-            }
-        } elseif ($kind === 'param') {
-            if (is_a($possibleSubtype, $type, true)) {
-                return true;
-            }
+        if (is_a($possibleSubtype, $type, true)) {
+            return true;
         }
 
         if (in_array($possibleSubtype, ['array', 'Traversable'], true) && $type === 'iterable') {
diff --git a/packages/TypeDeclaration/src/Rector/FunctionLike/ParamTypeDeclarationRector.php b/packages/TypeDeclaration/src/Rector/FunctionLike/ParamTypeDeclarationRector.php
index 2599b888b845..740ff01f989a 100644
--- a/packages/TypeDeclaration/src/Rector/FunctionLike/ParamTypeDeclarationRector.php
+++ b/packages/TypeDeclaration/src/Rector/FunctionLike/ParamTypeDeclarationRector.php
@@ -143,7 +143,7 @@ public function refactor(Node $node): ?Node
                 $possibleOverrideNewReturnType = $paramTypeInfo->getFqnTypeNode();
                 if ($possibleOverrideNewReturnType !== null) {
                     if ($paramNode->type !== null) {
-                        if ($this->isSubtypeOf($possibleOverrideNewReturnType, $paramNode->type, 'param')) {
+                        if ($this->isSubtypeOf($possibleOverrideNewReturnType, $paramNode->type)) {
                             // allow override
                             $paramNode->type = $paramTypeInfo->getFqnTypeNode();
                         }
diff --git a/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php b/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php
index 5654136c1350..cb20952d1231 100644
--- a/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php
+++ b/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php
@@ -3,7 +3,6 @@
 namespace Rector\TypeDeclaration\Rector\FunctionLike;
 
 use PhpParser\Node;
-use PhpParser\Node\Stmt\Class_;
 use PhpParser\Node\Stmt\ClassLike;
 use PhpParser\Node\Stmt\ClassMethod;
 use PhpParser\Node\Stmt\Function_;
@@ -16,6 +15,9 @@
 use Rector\TypeDeclaration\TypeInferer\ReturnTypeInferer;
 use Rector\TypeDeclaration\TypeInferer\ReturnTypeInferer\ReturnTypeDeclarationReturnTypeInferer;
 
+/**
+ * @sponsor Thanks https://spaceflow.io/ for sponsoring this rule - visit them on https://github.com/SpaceFlow-app
+ */
 final class ReturnTypeDeclarationRector extends AbstractTypeDeclarationRector
 {
     /**
@@ -33,10 +35,19 @@ final class ReturnTypeDeclarationRector extends AbstractTypeDeclarationRector
      */
     private $typeAnalyzer;
 
-    public function __construct(ReturnTypeInferer $returnTypeInferer, TypeAnalyzer $typeAnalyzer)
-    {
+    /**
+     * @var bool
+     */
+    private $overrideExistingReturnTypes = true;
+
+    public function __construct(
+        ReturnTypeInferer $returnTypeInferer,
+        TypeAnalyzer $typeAnalyzer,
+        bool $overrideExistingReturnTypes = true
+    ) {
         $this->returnTypeInferer = $returnTypeInferer;
         $this->typeAnalyzer = $typeAnalyzer;
+        $this->overrideExistingReturnTypes = $overrideExistingReturnTypes;
     }
 
     public function getDefinition(): RectorDefinition
@@ -90,11 +101,6 @@ public function refactor(Node $node): ?Node
             return null;
         }
 
-        $hasNewType = false;
-        if ($node->returnType !== null) {
-            $hasNewType = $node->returnType->getAttribute(self::HAS_NEW_INHERITED_TYPE, false);
-        }
-
         $inferedTypes = $this->returnTypeInferer->inferFunctionLikeWithExcludedInferers(
             $node,
             [ReturnTypeDeclarationReturnTypeInferer::class]
@@ -105,30 +111,31 @@ public function refactor(Node $node): ?Node
         }
 
         $returnTypeInfo = new ReturnTypeInfo($inferedTypes, $this->typeAnalyzer, $inferedTypes);
+        if ($this->isReturnTypeAlreadyAdded($node, $returnTypeInfo)) {
+            return null;
+        }
 
-        // @todo is it violation?
-        if ($hasNewType) {
-            // should override - is it subtype?
-            $possibleOverrideNewReturnType = $returnTypeInfo->getFqnTypeNode();
-            if ($possibleOverrideNewReturnType !== null) {
-                if ($node->returnType !== null) {
-                    if ($this->isSubtypeOf($possibleOverrideNewReturnType, $node->returnType, 'return')) {
-                        // allow override
-                        $node->returnType = $returnTypeInfo->getFqnTypeNode();
-                    }
-                } else {
-                    $node->returnType = $returnTypeInfo->getFqnTypeNode();
-                }
-            }
-        } else {
-            if ($this->isReturnTypeAlreadyAdded($node, $returnTypeInfo)) {
-                return null;
+        $shouldPopulateChildren = false;
+        // should be previous overridden?
+        if ($node->returnType !== null && $returnTypeInfo->getFqnTypeNode() !== null) {
+            $isSubtype = $this->isSubtypeOf($returnTypeInfo->getFqnTypeNode(), $node->returnType);
+
+            // @see https://wiki.php.net/rfc/covariant-returns-and-contravariant-parameters
+            if ($this->isAtLeastPhpVersion('7.4') && $isSubtype) {
+                $shouldPopulateChildren = true;
+                $node->returnType = $returnTypeInfo->getFqnTypeNode();
+            } elseif ($isSubtype === false) { // type override
+                $shouldPopulateChildren = true;
+                $node->returnType = $returnTypeInfo->getFqnTypeNode();
             }
-
+        } elseif ($returnTypeInfo->getFqnTypeNode() !== null) {
+            $shouldPopulateChildren = true;
             $node->returnType = $returnTypeInfo->getFqnTypeNode();
         }
 
-        $this->populateChildren($node, $returnTypeInfo);
+        if ($shouldPopulateChildren) {
+            $this->populateChildren($node, $returnTypeInfo);
+        }
 
         return $node;
     }
@@ -152,14 +159,10 @@ private function populateChildren(Node $node, ReturnTypeInfo $returnTypeInfo): v
             throw new ShouldNotHappenException(__METHOD__ . '() on line ' . __LINE__);
         }
 
-        $childrenClassLikes = $this->parsedNodesByType->findClassesAndInterfacesByType($className);
+        $childrenClassLikes = $this->parsedNodesByType->findChildrenOfClass($className);
 
         // update their methods as well
         foreach ($childrenClassLikes as $childClassLike) {
-            if (! $childClassLike instanceof Class_) {
-                continue;
-            }
-
             $usedTraits = $this->parsedNodesByType->findUsedTraitsInClass($childClassLike);
             foreach ($usedTraits as $trait) {
                 $this->addReturnTypeToMethod($trait, $node, $returnTypeInfo);
@@ -193,9 +196,6 @@ private function addReturnTypeToMethod(
 
         $currentClassMethod->returnType = $resolvedChildType;
 
-        // let the method now it was changed now
-        $currentClassMethod->returnType->setAttribute(self::HAS_NEW_INHERITED_TYPE, true);
-
         $this->notifyNodeChangeFileInfo($currentClassMethod);
     }
 
@@ -204,6 +204,12 @@ private function addReturnTypeToMethod(
      */
     private function shouldSkip(Node $node): bool
     {
+        if ($this->overrideExistingReturnTypes === false) {
+            if ($node->returnType) {
+                return true;
+            }
+        }
+
         if (! $node instanceof ClassMethod) {
             return false;
         }
@@ -220,6 +226,15 @@ private function isReturnTypeAlreadyAdded(Node $node, ReturnTypeInfo $returnType
             return true;
         }
 
+        // prevent overriding self with itself
+        if ($this->print($node->returnType) === 'self') {
+            $className = $node->getAttribute(AttributeKey::CLASS_NAME);
+
+            if (ltrim($this->print($returnTypeInfo->getFqnTypeNode()), '\\') === $className) {
+                return true;
+            }
+        }
+
         return false;
     }
 }
diff --git a/packages/TypeDeclaration/src/Rector/Property/PropertyTypeDeclarationRector.php b/packages/TypeDeclaration/src/Rector/Property/PropertyTypeDeclarationRector.php
index d185d27bedac..f662317c61b4 100644
--- a/packages/TypeDeclaration/src/Rector/Property/PropertyTypeDeclarationRector.php
+++ b/packages/TypeDeclaration/src/Rector/Property/PropertyTypeDeclarationRector.php
@@ -10,7 +10,6 @@
 use Rector\Rector\AbstractRector;
 use Rector\RectorDefinition\RectorDefinition;
 use Rector\TypeDeclaration\TypeInferer\PropertyTypeInferer;
-use Rector\TypeDeclaration\ValueObject\IdentifierValueObject;
 
 /**
  * @sponsor Thanks https://spaceflow.io/ for sponsoring this rule - visit them on https://github.com/SpaceFlow-app
@@ -61,20 +60,10 @@ public function refactor(Node $node): ?Node
 
         $types = $this->propertyTypeInferer->inferProperty($node);
         if ($types) {
-            $this->setNodeVarTypes($node, $types);
+            $this->docBlockManipulator->changeVarTag($node, $types);
             return $node;
         }
 
         return null;
     }
-
-    /**
-     * @param string[]|IdentifierValueObject[] $varTypes
-     */
-    private function setNodeVarTypes(Node $node, array $varTypes): Node
-    {
-        $this->docBlockManipulator->changeVarTag($node, $varTypes);
-
-        return $node;
-    }
 }
diff --git a/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer.php b/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer.php
index c7f90271b408..6dac5bdee35b 100644
--- a/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer.php
+++ b/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer.php
@@ -26,9 +26,9 @@ public function __construct(array $propertyTypeInferers)
      */
     public function inferProperty(Property $property): array
     {
-        foreach ($this->propertyTypeInferers as $propertyTypeInferers) {
-            $types = $propertyTypeInferers->inferProperty($property);
-            if ($types !== []) {
+        foreach ($this->propertyTypeInferers as $propertyTypeInferer) {
+            $types = $propertyTypeInferer->inferProperty($property);
+            if ($types !== [] && $types !== ['mixed']) {
                 return $types;
             }
         }
diff --git a/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer/GetterPropertyTypeInferer.php b/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer/GetterPropertyTypeInferer.php
index 86ce53f03185..6aea7f05c2f0 100644
--- a/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer/GetterPropertyTypeInferer.php
+++ b/packages/TypeDeclaration/src/TypeInferer/PropertyTypeInferer/GetterPropertyTypeInferer.php
@@ -58,7 +58,7 @@ public function inferProperty(Property $property): array
             }
 
             $returnTypes = $this->inferClassMethodReturnTypes($classMethod);
-            if ($returnTypes !== []) {
+            if ($returnTypes !== [] && $returnTypes !== ['mixed']) {
                 return $returnTypes;
             }
         }
@@ -107,7 +107,7 @@ private function inferClassMethodReturnTypes(ClassMethod $classMethod): array
         }
 
         $inferedTypes = $this->returnedNodesReturnTypeInferer->inferFunctionLike($classMethod);
-        if ($inferedTypes) {
+        if ($inferedTypes !== [] && $inferedTypes !== ['mixed']) {
             return $inferedTypes;
         }
 
diff --git a/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer.php b/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer.php
index 76dd045d082c..a3edd583328b 100644
--- a/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer.php
+++ b/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer.php
@@ -3,6 +3,7 @@
 namespace Rector\TypeDeclaration\TypeInferer;
 
 use PhpParser\Node\FunctionLike;
+use Rector\Exception\ShouldNotHappenException;
 use Rector\TypeDeclaration\Contract\TypeInferer\ReturnTypeInfererInterface;
 
 final class ReturnTypeInferer extends AbstractPriorityAwareTypeInferer
@@ -25,14 +26,7 @@ public function __construct(array $returnTypeInferers)
      */
     public function inferFunctionLike(FunctionLike $functionLike): array
     {
-        foreach ($this->returnTypeInferers as $returnTypeInferer) {
-            $types = $returnTypeInferer->inferFunctionLike($functionLike);
-            if ($types !== []) {
-                return $types;
-            }
-        }
-
-        return [];
+        return $this->inferFunctionLikeWithExcludedInferers($functionLike, []);
     }
 
     /**
@@ -42,18 +36,43 @@ public function inferFunctionLike(FunctionLike $functionLike): array
     public function inferFunctionLikeWithExcludedInferers(FunctionLike $functionLike, array $excludedInferers): array
     {
         foreach ($this->returnTypeInferers as $returnTypeInferer) {
-            foreach ($excludedInferers as $excludedInferer) {
-                if (is_a($returnTypeInferer, $excludedInferer, true)) {
-                    continue 2;
-                }
+            if ($this->shouldSkipExcludedTypeInferer($returnTypeInferer, $excludedInferers)) {
+                continue;
             }
 
             $types = $returnTypeInferer->inferFunctionLike($functionLike);
-            if ($types !== []) {
+            if ($types !== [] && $types !== ['mixed']) {
                 return $types;
             }
         }
 
         return [];
     }
+
+    /**
+     * @param string[] $excludedInferers
+     */
+    private function shouldSkipExcludedTypeInferer(
+        ReturnTypeInfererInterface $returnTypeInferer,
+        array $excludedInferers
+    ): bool {
+        foreach ($excludedInferers as $excludedInferer) {
+            $this->ensureIsTypeInferer($excludedInferer);
+
+            if (is_a($returnTypeInferer, $excludedInferer)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private function ensureIsTypeInferer(string $excludedInferer): void
+    {
+        if (is_a($excludedInferer, ReturnTypeInfererInterface::class, true)) {
+            return;
+        }
+
+        throw new ShouldNotHappenException();
+    }
 }
diff --git a/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedNodesReturnTypeInferer.php b/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedNodesReturnTypeInferer.php
index d5d154c8980d..6b03d37d057c 100644
--- a/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedNodesReturnTypeInferer.php
+++ b/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedNodesReturnTypeInferer.php
@@ -58,16 +58,15 @@ public function getPriority(): int
     }
 
     /**
-     * @param ClassMethod|Closure|Function_ $functionLike
      * @return Return_[]
      */
     private function collectReturns(FunctionLike $functionLike): array
     {
         $returns = [];
 
-        $this->callableNodeTraverser->traverseNodesWithCallable((array) $functionLike->stmts, function (Node $node) use (
-            &$returns
-        ): ?int {
+        $this->callableNodeTraverser->traverseNodesWithCallable((array) $functionLike->getStmts(), function (
+            Node $node
+        ) use (&$returns): ?int {
             if ($node instanceof Function_ || $node instanceof Closure || $node instanceof ArrowFunction) {
                 // skip Return_ nodes in nested functions
                 return NodeTraverser::DONT_TRAVERSE_CHILDREN;
diff --git a/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedPropertyReturnTypeInferer.php b/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedPropertyReturnTypeInferer.php
deleted file mode 100644
index be78fda84455..000000000000
--- a/packages/TypeDeclaration/src/TypeInferer/ReturnTypeInferer/ReturnedPropertyReturnTypeInferer.php
+++ /dev/null
@@ -1,118 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace Rector\TypeDeclaration\TypeInferer\ReturnTypeInferer;
-
-use PhpParser\Node\Expr\Closure;
-use PhpParser\Node\Expr\PropertyFetch;
-use PhpParser\Node\FunctionLike;
-use PhpParser\Node\Stmt\Class_;
-use PhpParser\Node\Stmt\ClassMethod;
-use PhpParser\Node\Stmt\Expression;
-use PhpParser\Node\Stmt\Function_;
-use PhpParser\Node\Stmt\Interface_;
-use PhpParser\Node\Stmt\Property;
-use PhpParser\Node\Stmt\Return_;
-use PhpParser\Node\Stmt\Trait_;
-use Rector\NodeTypeResolver\Node\AttributeKey;
-use Rector\TypeDeclaration\Contract\TypeInferer\ReturnTypeInfererInterface;
-use Rector\TypeDeclaration\TypeInferer\AbstractTypeInferer;
-use Rector\TypeDeclaration\TypeInferer\PropertyTypeInferer;
-use Rector\TypeDeclaration\ValueObject\IdentifierValueObject;
-
-/**
- * Infer return type from $this->variable → and get type $this->variable from @var annotation
- */
-final class ReturnedPropertyReturnTypeInferer extends AbstractTypeInferer implements ReturnTypeInfererInterface
-{
-    /**
-     * @var PropertyTypeInferer
-     */
-    private $propertyTypeInferer;
-
-    public function __construct(PropertyTypeInferer $propertyTypeInferer)
-    {
-        $this->propertyTypeInferer = $propertyTypeInferer;
-    }
-
-    /**
-     * @param ClassMethod|Closure|Function_ $functionLike
-     * @return string[]|IdentifierValueObject[]
-     */
-    public function inferFunctionLike(FunctionLike $functionLike): array
-    {
-        if (! $functionLike instanceof ClassMethod) {
-            return [];
-        }
-
-        $propertyFetch = $this->matchSingleStmtReturnPropertyFetch($functionLike);
-        if ($propertyFetch === null) {
-            return [];
-        }
-
-        $property = $this->getPropertyByPropertyFetch($propertyFetch);
-        if ($property === null) {
-            return [];
-        }
-
-        return $this->propertyTypeInferer->inferProperty($property);
-    }
-
-    public function getPriority(): int
-    {
-        return 700;
-    }
-
-    private function matchSingleStmtReturnPropertyFetch(ClassMethod $classMethod): ?PropertyFetch
-    {
-        if (count((array) $classMethod->stmts) !== 1) {
-            return null;
-        }
-
-        $singleStmt = $classMethod->stmts[0];
-        if ($singleStmt instanceof Expression) {
-            $singleStmt = $singleStmt->expr;
-        }
-
-        // is it return?
-        if (! $singleStmt instanceof Return_) {
-            return null;
-        }
-
-        if (! $singleStmt->expr instanceof PropertyFetch) {
-            return null;
-        }
-
-        $propertyFetch = $singleStmt->expr;
-        if (! $this->nameResolver->isName($propertyFetch->var, 'this')) {
-            return null;
-        }
-
-        return $propertyFetch;
-    }
-
-    private function getPropertyByPropertyFetch(PropertyFetch $propertyFetch): ?Property
-    {
-        /** @var Class_|Trait_|Interface_|null $class */
-        $class = $propertyFetch->getAttribute(AttributeKey::CLASS_NODE);
-        if ($class === null) {
-            return null;
-        }
-
-        /** @var string $propertyName */
-        $propertyName = $this->nameResolver->getName($propertyFetch->name);
-
-        foreach ($class->stmts as $stmt) {
-            if (! $stmt instanceof Property) {
-                continue;
-            }
-
-            if (! $this->nameResolver->isName($stmt, $propertyName)) {
-                continue;
-            }
-
-            return $stmt;
-        }
-
-        return null;
-    }
-}
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CorrectionTest.php b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CorrectionTest.php
index 45b00cb0c2de..8948ff152ec8 100644
--- a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CorrectionTest.php
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CorrectionTest.php
@@ -10,10 +10,10 @@ final class CorrectionTest extends AbstractRectorTestCase
     public function test(): void
     {
         $this->doTestFiles([
-            //            __DIR__ . '/Fixture/Correction/constructor_property_assign_over_getter.php.inc',
+            __DIR__ . '/Fixture/Correction/constructor_property_assign_over_getter.php.inc',
             __DIR__ . '/Fixture/Correction/prefix_fqn.php.inc',
             // skip
-            //            __DIR__ . '/Fixture/Correction/skip_override_of_the_same_class.php.inc',
+            __DIR__ . '/Fixture/Correction/skip_override_of_the_same_class.php.inc',
         ]);
     }
 
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CovarianceTest.php b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CovarianceTest.php
new file mode 100644
index 000000000000..df338dad52b0
--- /dev/null
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/CovarianceTest.php
@@ -0,0 +1,43 @@
+<?php declare(strict_types=1);
+
+namespace Rector\TypeDeclaration\Tests\Rector\FunctionLike\ReturnTypeDeclarationRector;
+
+use Rector\Testing\PHPUnit\AbstractRectorTestCase;
+use Rector\TypeDeclaration\Rector\FunctionLike\ReturnTypeDeclarationRector;
+use Symplify\PackageBuilder\Parameter\ParameterProvider;
+
+final class CovarianceTest extends AbstractRectorTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $parameterProvider = self::$container->get(ParameterProvider::class);
+        $parameterProvider->changeParameter('php_version_features', '7.0');
+    }
+
+    /**
+     * Needed to restore previous version
+     */
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        $parameterProvider = self::$container->get(ParameterProvider::class);
+        $parameterProvider->changeParameter('php_version_features', '10.0');
+    }
+
+    public function test(): void
+    {
+        $this->doTestFiles([
+            __DIR__ . '/Fixture/nikic/inheritance_covariance.php.inc',
+            __DIR__ . '/Fixture/Covariance/return_interface_to_class.php.inc',
+            __DIR__ . '/Fixture/Covariance/return_nullable_with_parent_interface.php.inc',
+        ]);
+    }
+
+    protected function getRectorClass(): string
+    {
+        return ReturnTypeDeclarationRector::class;
+    }
+}
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Correction/prefix_fqn.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Correction/prefix_fqn.php.inc
index 49bf7874a9db..970a97822049 100644
--- a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Correction/prefix_fqn.php.inc
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Correction/prefix_fqn.php.inc
@@ -5,7 +5,7 @@ namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationR
 use Rector\TypeDeclaration\Tests\Rector\FunctionLike\ReturnTypeDeclarationRector\Source\RealReturnedClass;
 use Rector\TypeDeclaration\Tests\Rector\FunctionLike\ReturnTypeDeclarationRector\Source\ReturnedClass;
 
-class SkipOverrideOfTheSameClass
+class PrefixFqn
 {
     public function getReturnedClass(): ReturnedClass
     {
@@ -22,7 +22,7 @@ namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationR
 use Rector\TypeDeclaration\Tests\Rector\FunctionLike\ReturnTypeDeclarationRector\Source\RealReturnedClass;
 use Rector\TypeDeclaration\Tests\Rector\FunctionLike\ReturnTypeDeclarationRector\Source\ReturnedClass;
 
-class SkipOverrideOfTheSameClass
+class PrefixFqn
 {
     public function getReturnedClass(): \Rector\TypeDeclaration\Tests\Rector\FunctionLike\ReturnTypeDeclarationRector\Source\RealReturnedClass
     {
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Covariance/return_interface_to_class.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Covariance/return_interface_to_class.php.inc
new file mode 100644
index 000000000000..79ca8637d886
--- /dev/null
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Covariance/return_interface_to_class.php.inc
@@ -0,0 +1,17 @@
+<?php
+
+namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture\Covariance;
+
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Input\InputInterface;
+
+interface CommandInterface {
+    public function getInput(): InputInterface;
+}
+
+class SomeCommand implements CommandInterface {
+    public function getInput(): InputInterface
+    {
+        return new ArrayInput([]);
+    }
+}
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Covariance/return_nullable_with_parent_interface.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Covariance/return_nullable_with_parent_interface.php.inc
new file mode 100644
index 000000000000..322e0f13ab12
--- /dev/null
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/Covariance/return_nullable_with_parent_interface.php.inc
@@ -0,0 +1,14 @@
+<?php
+
+namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture\Covariance;
+
+interface UserInterface {
+    public function getName(): ?string;
+}
+
+class User implements UserInterface {
+    public function getName(): ?string
+    {
+        return null;
+    }
+}
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/inheritance_covariance.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/inheritance_covariance.php.inc
index a1193573d8c2..c014174b059a 100644
--- a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/inheritance_covariance.php.inc
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/inheritance_covariance.php.inc
@@ -41,7 +41,7 @@ class CCovariance extends ACovariance {
      *
      * @return CCovariance
      */
-    public function test(): \Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture\Inheritance\CCovariance {
+    public function test(): \Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture\Inheritance\ACovariance {
         return $this;
     }
 }
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/object_php72.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/object_php72.php.inc
index ebd6962a27e0..1095fa7dd65a 100644
--- a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/object_php72.php.inc
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nikic/object_php72.php.inc
@@ -28,7 +28,7 @@ class A {
 }
 class B extends A {
     /** @return Foo */
-    public function getObject($value): \Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture\ObjectPhp72\Foo {
+    public function getObject($value): object {
         return $value;
     }
 }
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_mixed_and_string.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_mixed_and_string.php.inc
new file mode 100644
index 000000000000..29db67e19f08
--- /dev/null
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_mixed_and_string.php.inc
@@ -0,0 +1,25 @@
+<?php
+
+namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture;
+
+use stdClass;
+
+class SkipMixedAndString
+{
+    /** @var mixed */
+    protected $value;
+
+    public function getValue()
+    {
+        if ($this->value instanceof stdClass) {
+            return $this->getStringValue();
+        }
+
+        return $this->value;
+    }
+
+    public function getStringValue(): string
+    {
+        return 'abc';
+    }
+}
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_self.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_self.php.inc
new file mode 100644
index 000000000000..bab980fca004
--- /dev/null
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_self.php.inc
@@ -0,0 +1,11 @@
+<?php
+
+namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture;
+
+class SkipSelf
+{
+    public function getSelf(): self
+    {
+        return new self();
+    }
+}
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Php72RectorTest.php b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Php72RectorTest.php
index af66077180d4..054d3be23f58 100644
--- a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Php72RectorTest.php
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Php72RectorTest.php
@@ -13,7 +13,18 @@ protected function setUp(): void
         parent::setUp();
 
         $parameterProvider = self::$container->get(ParameterProvider::class);
-        $parameterProvider->changeParameter('    php_version_features', '7.0');
+        $parameterProvider->changeParameter('php_version_features', '7.0');
+    }
+
+    /**
+     * Needed to restore previous version
+     */
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        $parameterProvider = self::$container->get(ParameterProvider::class);
+        $parameterProvider->changeParameter('php_version_features', '10.0');
     }
 
     public function test(): void
diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/ReturnTypeDeclarationRectorTest.php b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/ReturnTypeDeclarationRectorTest.php
index e27cf0f61ab0..c5a31a5d7cdd 100644
--- a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/ReturnTypeDeclarationRectorTest.php
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/ReturnTypeDeclarationRectorTest.php
@@ -5,14 +5,13 @@
 use Rector\Testing\PHPUnit\AbstractRectorTestCase;
 use Rector\TypeDeclaration\Rector\FunctionLike\ReturnTypeDeclarationRector;
 
-/**
- * @sponsor Thanks https://spaceflow.io/ for sponsoring this rule - visit them on https://github.com/SpaceFlow-app
- */
 final class ReturnTypeDeclarationRectorTest extends AbstractRectorTestCase
 {
     public function test(): void
     {
         $files = [
+            __DIR__ . '/Fixture/skip_mixed_and_string.php.inc',
+            __DIR__ . '/Fixture/skip_self.php.inc',
             // static types
             __DIR__ . '/Fixture/void_type.php.inc',
             __DIR__ . '/Fixture/no_void_abstract.php.inc',
@@ -67,7 +66,6 @@ public function testInheritance(): void
     {
         $files = [
             __DIR__ . '/Fixture/nikic/inheritance.php.inc',
-            __DIR__ . '/Fixture/nikic/inheritance_covariance.php.inc',
             __DIR__ . '/Fixture/nikic/nullable_inheritance.php.inc',
         ];
 
diff --git a/packages/TypeDeclaration/tests/Rector/Property/PropertyTypeDeclarationRector/Fixture/constructor_array_param_with_nullable.php.inc b/packages/TypeDeclaration/tests/Rector/Property/PropertyTypeDeclarationRector/Fixture/constructor_array_param_with_nullable.php.inc
index d0a5b73fed94..fbee723d8e59 100644
--- a/packages/TypeDeclaration/tests/Rector/Property/PropertyTypeDeclarationRector/Fixture/constructor_array_param_with_nullable.php.inc
+++ b/packages/TypeDeclaration/tests/Rector/Property/PropertyTypeDeclarationRector/Fixture/constructor_array_param_with_nullable.php.inc
@@ -21,7 +21,7 @@ namespace Rector\TypeDeclaration\Tests\Rector\FunctionLike\PropertyTypeDeclarati
 class ConstructorArrayParamWithNullable
 {
     /**
-     * @var array|null
+     * @var mixed[]|null
      */
     private $data;