It's literally stated in the PEP: https://peps.python.org/pep-0681/ https://peps.python.org/pep-0681/ Also: https://github.com/python/mypy/blob/501a07b45af8e44

It's literally stated in the PEP: https://peps.python.org/pep-0681/ https://peps.python.org/pep-0681/ Also: https://github.com/python/mypy/blob/501a07b45af8e44eda665e53526fc590dc5a014e/mypy/semanal_shared.py#L376 https://github.com/python/mypy/blob/501a07b45af8e44eda665e53... Also did you know mypy ignores typing of class decorators? You simply can't return a different type other than type[thisclass].