This is why we have 4 months of betas :-)

On one hand making objects in `typing` module not classes was intentional, but on another hand this use case looks totally fine.

I would say we could update the check in `functools` to accept more things. I am however not sure what to allow here in addition to proper classes, maybe just anything that overrides `__subclasscheck__` and/or `__instancecheck__`? I could imagine there might be some other objects that implement custom instance and class checks beyond `typing` that are rejected by current checks in `functools`.

As a temporary workaround you can use `collections.abc.Sequence`, this type is aliased by `typing.Sequence`, in fact all instance checks etc. are relayed to the former.