This is the first time I heard about member and nomember, but I appreciate the opportunity to learn...

I played a little and found your fix does not cover the following slight change of your example:

from enum import Enum, member
from typing import reveal_type

class Pet(Enum):
    CAT = 1

    @member
    def human(self) -> int:
        return 2

def a(x: Pet) -> None:
    if x is not Pet.human:  # `human` instead of `CAT`, as in the original example
        reveal_type(x)  # N: Revealed type is "__main__.Pet"

Expected would be Literal[__main__.Pet.CAT]

However, this does not seem to be related to TypeInfo.enum_members, so this comment is just a suggestion for an extension of this or an independent PR.

Because of my lack of experience, I am not really sure if some edge cases are missed, but to me, this change looks good and is definitely an improvement.