Could reproduce issue with 4 test cases in windows with Python 3.9:

python -Om test -j2 test_clinic test_coroutines test_dis test_imaplib test_multiprocessing_forkserver test_multiprocess
ing_spawn test_py_compile test_sys_settrace test_wsgiref test_zipimport
0:00:00 Run tests in parallel using 2 child processes
0:00:01 [ 1/10] test_clinic skipped
test_clinic skipped -- clinic directory could not be found
0:00:01 [ 2/10/1] test_coroutines failed
test test_coroutines failed -- Traceback (most recent call last):
File "...\test\test_coroutines.py", line 1265, in test_with_5
run_async(func())
AssertionError: AssertionError not raised
0:00:31 load avg: 0.00 running: test_dis (30.0 sec), test_imaplib (30.0 sec)
0:00:36 load avg: 0.00 [ 3/10/1] test_dis passed -- running: test_imaplib (34.8 sec)
0:00:36 load avg: 0.00 [ 4/10/1] test_imaplib passed (34.4 sec)
0:01:06 load avg: 0.22 running: test_multiprocessing_forkserver (30.0 sec), test_multiprocessing_spawn (30.0 sec)
0:01:36 load avg: 0.16 running: test_multiprocessing_forkserver (1 min), test_multiprocessing_spawn (1 min)
0:01:58 load avg: 0.11 [ 5/10/1] test_multiprocessing_forkserver skipped -- running: test_multiprocessing_spawn (1 min 22 sec)
test_multiprocessing_forkserver skipped -- forkserver is not available on Windows
0:01:58 load avg: 0.11 [ 6/10/1] test_multiprocessing_spawn passed (1 min 21 sec)
0:01:59 load avg: 0.11 [ 7/10/1] test_sys_settrace passed
0:01:59 load avg: 0.11 [ 8/10/2] test_py_compile failed
test test_py_compile failed -- multiple errors occurred; run in verbose mode for details
0:01:59 load avg: 0.11 [ 9/10/3] test_wsgiref failed
test test_wsgiref failed -- multiple errors occurred; run in verbose mode for details
0:01:59 load avg: 0.11 [10/10/4] test_zipimport failed
test test_zipimport failed -- multiple errors occurred; run in verbose mode for details
== Tests result: FAILURE ==
4 tests OK.
4 tests failed:
test_coroutines test_py_compile test_wsgiref test_zipimport
2 tests skipped:
test_clinic test_multiprocessing_forkserver
Total duration: 1 min 59 sec
Tests result: FAILURE

python -m test -j2 test_coroutines test_py_compile test_wsgiref test_zipimport
0:00:00 Run tests in parallel using 2 child processes
0:00:01 [1/4] test_py_compile passed
0:00:01 [2/4] test_coroutines passed
0:00:02 [3/4] test_wsgiref passed
0:00:02 [4/4] test_zipimport passed
== Tests result: SUCCESS ==
All 4 tests OK.

Was able to reproduce this. I have a draft PR here: #93174 😃