right order of priorities

by getting the value - if it's unique, first getting the defaults before creating an unique value.

Fix #20067

src/core/qgsvectorlayerutils.cpp

@@ -381,17 +381,10 @@ QgsFeature QgsVectorLayerUtils::createFeature( const QgsVectorLayer *layer, cons
 
     // in order of priority:
     // 1. passed attribute value and if field does not have a unique constraint like primary key
-    if ( attributes.contains( idx ) )
+    if ( attributes.contains( idx )
+         && !( fields.at( idx ).constraints().constraints() & QgsFieldConstraints::ConstraintUnique ) )
     {
       v = attributes.value( idx );
-      if ( fields.at( idx ).constraints().constraints() & QgsFieldConstraints::ConstraintUnique
-           && QgsVectorLayerUtils::valueExists( layer, idx, v ) )
-      {
-        // unique constraint violated
-        QVariant uniqueValue = QgsVectorLayerUtils::createUniqueValue( layer, idx, v );
-        if ( uniqueValue.isValid() )
-          v = uniqueValue;
-      }
       checkUnique = false;
     }