unittest.addModuleCleanup has no effect

Given this test file:

from contextlib import contextmanager
import unittest

print("Module load")


def module_cleanup_hook():
    print("module_cleanup_hook")


@contextmanager
def module_cleanup_contextmanager():
    print("module_cleanup_contextmanager enter")
    yield
    print("module_cleanup_contextmanager exit")


def setUpModule():
    print("setUpModule")


def tearDownModule():
    print("tearDownModule")


unittest.addModuleCleanup(module_cleanup_hook)

unittest.enterModuleContext(module_cleanup_contextmanager())


class Test(unittest.TestCase):
    def test(self) -> None:
        pass

I get:

$ pytest test.py -qs
Module load
module_cleanup_contextmanager enter
setUpModule
.tearDownModule

1 passed in 0.11s

which show that while unittest-style setUpModule and tearDownModule get called, addModuleCleanup does not seem to be, which also breaks enterModuleContext, that is built on top of it.

I am using pytest 9.1.1-1~bpo13+1 from backports in a clean Debian Stable chroot, and the result is the same with 8.3.5-2.

Reproduce the report with the shown test.py and run pytest test.py -qs. Trace pytest's unittest-style module setup and teardown handling, focusing on why unittest.addModuleCleanup is not executed. Done means the cleanup hook runs and the context manager prints its exit message after tearDownModule.