weakref.WeakMethod equality behaves differently than weakref.ref (always False after garbage collection)

Bug report

Equality comparison of weakref.ref objects succeeds both before and after object deletion. Equality of two weakref.WeakMethod objects, however, is always false if the underlying object has been deleted:

>>> from weakref import WeakMethod, ref
>>> class T:
...   def x(self): ...
...
>>> t = T()
>>> r1 = ref(t)
>>> r2 = ref(t)
>>> m1 = WeakMethod(t.x)
>>> m2 = WeakMethod(t.x)
>>> r1 == r2
True
>>> m1 == m2
True
>>> del t
>>> r1 == r2
True
>>> m1 == m2
False

Is this a bug? or perhaps desirable behavior or a fundamental limitation of bound method weak references?

Your environment

• Python 3.11.0 | packaged by conda-forge | (main, Jan 15 2023, 05:44:48) [Clang 14.0.6 ] on darwin
• macos x86_64, v12.6.1 (21G217)

Start by running the provided Python REPL example and compare weakref.ref with weakref.WeakMethod before and after garbage collection. Then inspect the WeakMethod and ref implementations and their equality-related tests, if present. Done means establishing the intended post-deletion equality semantics and adding coverage or a focused fix if the behavior is confirmed as a bug.