ISTM collections is the correct module reference because that is where the code is actually defined.  A debugging tool should look there instead of in the calling code.  This is the way other tools work in Python as well:

    >>> from collections.abc import Set
    >>> class S(Set):
            def __init__(self): pass
            def __iter__(self): yield 0
            def __len__(self): return 0
            def __contains__(self, key): return False
            
    >>> S.__or__.__module__
    'collections.abc'

    >>> from dataclasses import make_dataclass
    >>> P = make_dataclass('P', ['x', 'y'])
    >>> P.__repr__.__module__
    'dataclasses'

Likewise, the various tools that use closures used to report the module where the closure was defined rather than the module of the caller's code (see functools.cmp_to_key or functools.lru_cache).  I say "used to" because the pure Python code is now supplanted by C equivalents where the __module__ attribute__ is appropriately set to None:

    # Running from PyPy
    >>>> from functools import cmp_to_key
    >>>> c = cmp_to_key(lambda x, y: 0)
    >>>> c.__init__.__module__
    '_functools'

The Data Model section of the Language Reference defines __module__ as follows, "__module__: The name of the module the function was defined in, or None if unavailable."  In the prior version of namedtuple(), the function was defined in a virtual module (an execed string).  Now, that the methods are defined in a real module, the __module__ attribute should name that real module.