Wrong unsoundness? #1330

The following reproducer code returns the __init__ method of a class:

from typing import Any
def f(cls: type) -> Any:
    return cls.__init__

but mypy considers that the __init__method was accessed from an instance:
main.py:4: error: Accessing "__init__" on an instance is unsound, since instance.__init__ could be from an incompatible subclass [misc]

Where is the problem?