Re-opening; I believe this issue is still valid.

Here's output on a debug build on current master (commit 7591d9455eb37525c832da3d65e1a7b3e6dbf613) on my machine:

lovelace:cpython mdickinson$ ./python.exe
Python 3.10.0a6+ (remotes/upstream/master:7591d9455e, Mar 13 2021, 12:04:31) [Clang 11.0.0 (clang-1100.0.33.17)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys, threading, time
>>> for _ in range(10):
...     threading.Thread().start()
...     time.sleep(0.1)
...     print(sys.gettotalrefcount())
... 
109901
109905
109907
109909
109911
109913
109915
109917
109919
109921