diff --git a/CHANGES b/CHANGES
index 6125b83a1da..7241391ae02 100644
--- a/CHANGES
+++ b/CHANGES
@@ -19,6 +19,7 @@ Bugs fixed
 * #8559: autodoc: AttributeError is raised when using forward-reference type
   annotations
 * #8568: autodoc: TypeError is raised on checking slots attribute
+* #8567: autodoc: Instance attributes are incorrectly added to Parent class
 
 Testing
 --------
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 4bf97cc851a..c12562efdd7 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -1856,13 +1856,14 @@ def can_document_member(cls, member: Any, membername: str, isattr: bool, parent:
     def update_annotations(self, parent: Any) -> None:
         """Update __annotations__ to support type_comment and so on."""
         try:
-            annotations = inspect.getannotations(parent)
+            annotations = dict(inspect.getannotations(parent))
+            parent.__annotations__ = annotations
 
             analyzer = ModuleAnalyzer.for_module(self.modname)
             analyzer.analyze()
             for (classname, attrname), annotation in analyzer.annotations.items():
                 if classname == '' and attrname not in annotations:
-                    annotations[attrname] = annotation  # type: ignore
+                    annotations[attrname] = annotation
         except AttributeError:
             pass
 
@@ -2292,7 +2293,8 @@ def isinstanceattribute(self) -> bool:
     def update_annotations(self, parent: Any) -> None:
         """Update __annotations__ to support type_comment and so on."""
         try:
-            annotations = inspect.getannotations(parent)
+            annotations = dict(inspect.getannotations(parent))
+            parent.__annotations__ = annotations
 
             for cls in inspect.getmro(parent):
                 try:
@@ -2303,7 +2305,7 @@ def update_annotations(self, parent: Any) -> None:
                     analyzer.analyze()
                     for (classname, attrname), annotation in analyzer.annotations.items():
                         if classname == qualname and attrname not in annotations:
-                            annotations[attrname] = annotation  # type: ignore
+                            annotations[attrname] = annotation
                 except (AttributeError, PycodeError):
                     pass
         except AttributeError: