mypy incorrectly marks a @staticmethod definition of an attribute A to be incompatible with A's signature in a parent class. #12569

Bug Report
When a class C defines an attribute a to be a union type with Callable as one of its types (a: Callable | ...), mypy incorrectly marks a @staticmethod definition of a in a child class that inherits from C to be incompatible with a's signature in C.

Worth noting that the following code produces no errors:

from typing import Callable


class Parent:
    foo: Callable[[str], str]

class Child2(Parent):
    @staticmethod
    def foo(x: str) -> str:
        return x.lower()

but the following code does

from typing import Callable


class Parent:
    foo: Callable[[str], str] | str 


class Child1(Parent):
    foo = "bar"  # OK


class Child2(Parent):
    @staticmethod
    def foo(x: str) -> str:  # Signature of "foo" incompatible with supertype "Parent"
        return x.lower()

Expected Behavior
No errors.

Actual Behavior

example.py: note: In class "Child2":
example.py:14: error: Signature of "foo" incompatible with supertype "Parent"  [override]
Found 1 error in 1 file (checked 1 source file)

Environment

• Mypy version used: 0.941
• Mypy command-line flags: --strict, --show-error-codes, --show-error-context
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.10.3
• Operating system and version: MacOS 12.3