Is there any reason users would care about this? Is there any real world impact?

The current result seems reasonable to me. The __new__ method was created virtually so it is fair to report it as `'namedtuple_MyTuple'. It has been this way for a very long time and has not been a source of problems.

Is there any reason users would care about this? Is there any real world impact?

I'm trying to improve namedtuple support in PyTorch Dynamo, an ML compiler backend with a lightweight Python interpreter. Dynamo traces the Python frames and generates performat inlined functions via traced opcodes. The __module__ attribute is used to reconstruct the Python function during codegen phase.

The codegen tries to import the __name__ attribute during creating the __new__ function for namedtuple

https://github.com/pytorch/pytorch/blob/bae951030752f2d7f06c15af0c59e54026d851e9/torch/_dynamo/symbolic_convert.py#L3290-L3299

    def get_globals_source_and_value(self, name):
        if "__name__" in self.f_globals:
            module_name = self.f_globals["__name__"]
            module_source = self.import_source(module_name)
            if "torch_package" in module_name:
                fglobals_value = torch.package.package_importer._package_imported_modules[module_name]  # type: ignore[assignment]
            else:
                fglobals_value = importlib.import_module(module_name)  # type: ignore[assignment]
            fglobals_vt = VariableTracker.build(self, fglobals_value, module_source)
            global_source = AttrSource(module_source, name)

For PyTorch is this a show stopper or is a workaround available?

How would MyTuple.__new__.__module__ returning __main__ actually be useful for reconstructing a __new__ method? That isn't clear to me from your post. That attribute doesn't affect functionality. Technically, a namedtuple doesn't have to live in a module at all. It can be execed dynamically, created and used within a function's locals, stored in a class definination, or stored in a data structure rather than a module's globals. In these circumstances, returning __main__ isn't really correct.