❯ py -3.8 -c 'from typing import TypedDict; print(type(TypedDict))'
<class 'typing._TypedDictMeta'>

❯ py -3.9 -c 'from typing import TypedDict; print(type(TypedDict))'
<class 'function'>

Python 3.9 changed the type of the TypedDict but the documentation still says it's a class - see https://docs.python.org/3.9/library/typing.html#typing.TypedDict. I must also say I'm suprised you can inherit from a function, but we should update the documentation to reflect that the type of the element in question is no longer class.