If an attribute alias reaches method missing, send the original

Fixes rails#51717

activemodel/lib/active_model/attribute_methods.rb

@@ -480,8 +480,14 @@ def method_missing(method, ...)
       if respond_to_without_attributes?(method, true)
         super
       else
-        match = matched_attribute_method(method.name)
-        match ? attribute_missing(match, ...) : super
+        # If the missing method is an attribute alias, let's send the original
+        # to +method_missing+ since it can actually produce a value.
+        if self.class.attribute_alias?(method) && self.class.send(:instance_method_already_implemented?, method)
+          super(self.class.attribute_alias(method).to_sym, ...)
+        else
+          match = matched_attribute_method(method.name)
+          match ? attribute_missing(match, ...) : super
+        end
       end
     end