That comment was in Bullseye. In Trixie's /etc/login.defs the comment is gone.
With Trixie, PAM's "User Private Groups" are by default enabled and default umask thus is 002 instead of 022.
(Personally, I'm irritated by the rather silent way this invasive change got introduced -- it is mentioned in /usr/share/doc/libpam-modules/NEWS.Debian.gz together with instructions to restore the old behavior.)
With Trixie, PAM's "User Private Groups" are by default enabled and default umask thus is 002 instead of 022.
(Personally, I'm irritated by the rather silent way this invasive change got introduced -- it is mentioned in /usr/share/doc/libpam-modules/NEWS.Debian.gz together with instructions to restore the old behavior.)