If you haven’t been handling .pacnew and .pacsave files then your problem is almost certainly related to the recent polkit update. Compare /etc/pam.d/polkit-1.pacsave (old) to /usr/lib/pam.d/polkit-1 (new) and merge changes as necessary.
This was very clearly pointed out in Known Issues for [Stable Update] 2024-02-21.