Weird [mis]interaction between generics and union

[ANogin]

Bug Report

In the following file

from typing import Generic, Sequence, Tuple, TypeVar

def f(
    x: Sequence[str], y: Sequence[int] | Sequence[bool]
) -> zip[Tuple[str, int]] | zip[Tuple[str, bool]]:
    return zip(x, y) # OK

T = TypeVar("T")

class C(Generic[T]):
    def g(
        self, x: Sequence[str], y: Sequence[T] | Sequence[bool]
    ) -> zip[Tuple[str, T]] | zip[Tuple[str, bool]]:
        return zip(x, y) # ERROR

mypy accepts f, but complains

error: Incompatible return value type (got "zip[tuple[str, object]]", expected "zip[tuple[str, T]] | zip[tuple[str, bool]]")  [return-value]

on the return from C.g

Confirmed with mypy 1.11.2 in Python 3.11.9, but does not seem version-specific.

P.S. My specific use case where I found this issue was where I had for (a,b) in zip(x,y), then was using b where Union[T|bool] was expected, and getting an error message from mypy that object (b) is used where T|bool was expected; I tried to simplify that code to digest it to the minimal reproducible example. I do not fully understand all the constraints here, but the fact that f is accepted and C.g is not does suggest to me that something is clearly wrong.