Argument "key" to "sorted" has incompatible type "Callable…"

Bug Report

I believe that I've found a bug in mypy, the following MRE should as far as I can tell not result in any typing errors at all, but it reports an error (and I've found two simple workarounds for which no error is reported, strengthening my belief that this is a bug and not intended behaviour).

To Reproduce

#!/usr/bin/python3

from collections.abc import Iterable
from typing import cast


def unproblematic(iter: Iterable[int]) -> None:
    print(iter)


def problematic(iter: Iterable[int | str]) -> None:
    print(iter)


def key(item: int) -> int:
    return -item


def main() -> None:
    items: list[int] = [3, 4, 1, 2]

    unproblematic(sorted(items, key=key))  # Works.
    problematic(sorted(items, key=key))  # Fails mypy arg-type.

    workaround = sorted(items, key=key)
    problematic(workaround)  # Works.

    problematic(cast(Iterable[int], sorted(items, key=key)))  # Works.


if __name__ == '__main__':
    main()

Actual Behavior

$ mypy mre.py
mre.py:23: error: Argument "key" to "sorted" has incompatible type "Callable[[int], int]"; expected "Callable[[int | str], SupportsDunderLT[Any] | SupportsDunderGT[Any]]"  [arg-type]

Your Environment

$ mypy --version                
mypy 1.16.0 (compiled: yes)
$ python3 --version
Python 3.13.3

(If anyone can't trivially reproduce this, I'd be happy to provide more details about my environment.)

Empieza reproduciendo el informe del MRE en mre.py con mypy 1.16.0 y Python 3.13.3; después, compara la llamada directa sorted(items, key=key) con las dos soluciones alternativas. Se considera terminado cuando la llamada directa ya no informe del argumento key incompatible y el ejemplo siga estando correctamente tipado.