False negative for invalid abstractmethod implementation

Bug Report
If a subclass of an ABC implements an abstractmethod as an attribute (e.g. not as method or class variable), (and the subclass is instantiated,) then mypy passes. But it will always fail at runtime (as ABCMeta can only detect variables/methods on the class).
There are only some cases where this can happen because implementing a method as an attribute would yield a mypy type error most of the time:

• an abstract property is implemented as a normal instance attribute
• an abstract method is implemented as a function instance attribute

Note: these implementations are valid both pragmatically and for type-checking, but ABCMeta is obligated to raise an error because it cannot detect the implementation.

To Reproduce
The following program will pass in mypy but fail at runtime.

from abc import abstractmethod, ABC
from collections.abc import Callable


class Method(ABC):
    @abstractmethod
    def f(self) -> None:
        ...

class ImplMethod(Method):
    f: Callable[[], None]
    def __init__(self):
        self.f = print

ImplMethod()


class Property(ABC):
    @property
    @abstractmethod
    def x(self) -> int:
        ...

class ImplProperty(Property):
    x: int
    def __init__(self):
        self.x = 2

ImplProperty()

Expected Behavior
Error at runtime.
Mypy should error too because the implementations do not satisfy abstractmethod at runtime.

Actual Behavior
Error at runtime.
Mypy success.

Your Environment

• Mypy version used: latest (1.11.1), with default playground flags
• Python version used: 3.12.4

Also:
It seems like mypy doesn't complain when using abstractmethod on a non-ABC class. This is intended, right?

Inizia con la riproduzione Python fornita e ispeziona la gestione di abstractmethod e ABC da parte di mypy; nell’issue non sono nominati file sorgente né test. Il lavoro è completato quando mypy rifiuta le implementazioni degli attributi di istanza mostrate e mantiene il comportamento previsto di abstractmethod sulle classi non-ABC.