Try this and reboot.
# Authentication
# install `sssd`
sudo dnf -yq install sssd
sudo systemctl enable sssd
# configure sssd for local authentication
sudo touch /etc/sssd/sssd.conf
sudo chmod 600 /etc/sssd/sssd.conf
echo "[domain/local]
id_provider = files
[sssd]
domains = local
services = nss, pam, ssh, sudo" |
sudo tee /etc/sssd/sssd.conf >/dev/null
# start `sssd`
sudo systemctl start sssd
# enable `sssd` `authselect` profile
sudo authselect select sssd \
--force \
without-nullok #\
# with-faillock #faillock optional, cockpit has a tendency to lock you out
It should restore normal local user functionality (assuming either sssd/authselect is the culprit). Also, I have gpasswd -a $user $group in my rhel scripts for adding groups. I don’t remember why, but maybe try that instead of usermod if you still have problems.