Comment 5 for bug 1999197

Sad story. Seems to be this problem:

[Bug 1960547] Re: please remove mailman3, mailman-hyperkitty

And from mailman3 upstream it seems that Python 3.10 is only supported in the (not yet released) 3.3.8 version:

https://docs.mailman3.org/projects/mailman/en/latest/src/mailman/docs/NEWS.html