Type not narrowed on `isinstance(obj, Callable)` check

I received this bug report from a pyright user: https://github.com/microsoft/pyright/issues/2274. Mypy exhibits the same behavior, so I'm wondering whether it's a bug or the intended behavior.

In this code sample, mypy (and pyright) do not currently narrow the type of obj based on the isinstance(obj, Callable) conditional check.

from typing import Callable, Union

def some_func(obj: Union[Callable, int]):
    if isinstance(obj, Callable):
        reveal_type(obj) # Type of "obj" is "(*args: Unknown, **kwargs: Unknown) -> Unknown | int"
    else:
        reveal_type(obj) # Type of "obj" is "(*args: Unknown, **kwargs: Unknown) -> Unknown | int"

I'm wondering if there's a reason why mypy does not perform type narrowing in this case. Is there a type safety reason? Is callable() the preferred way to check for callables?

I've searched the issue database, and it doesn't appear to be an issue that anyone has previously reported.

Beginne damit, den Python-Reproducer mit mypy auszuführen und die aufgedeckten Typen für beide Zweige zu prüfen. Verfolge das bestehende isinstance- und Callable-Narrowing-Verhalten, einschließlich aller zugehörigen Tests oder Dokumentation. Als abgeschlossen gilt, festzustellen, ob dieses Verhalten beabsichtigt ist, und, falls es ein Fehler ist, ein getestetes Narrowing-Ergebnis zu definieren.