Created a group with existing gid, now cannot delete it

I'm on Ubuntu 24. Originally, the system had an existing group with gid 999:

# cat /etc/group | grep 999
systemd-journal:x:999:

(I mistakenly tried to create a group with that duplicate ID: groupadd docker -g 999) - UPDATE: I originally thought I was responsible for creating the duplicate group ID, but after a bunch of troubleshooting, it seems that it was created by the LDAP server. So the prior statement is not correct. Now I'm stuck unable to add users to the group (properly) and unable to delete the docker group in order to start over. Firstly, there's no docker group in /etc/group:

# sudo cat /etc/group | grep docker

If I run getent group docker, then I get the users who are in the original group with gid 999 - those that belong to the systemd-journal group:

# getent group docker
docker:*:999:ausername,anotherusername,yetanotherusername

I can't change its gid:

# sudo groupmod -g 899 docker
groupmod: group 'docker' does not exist in /etc/group

I can't delete the docker group either:

# sudo groupdel docker
groupdel: cannot remove entry 'docker' from /etc/group

I'm also not allowed to create the docker group again:

# sudo groupadd -g 899 docker
groupadd: group 'docker' already exists

If I try to change the group of a file to be the docker, it'll actually assign the original group (systemd-journal) that gid 999 belongs to:

# sudo chown root:docker /tmp/foo
# ls -l /tmp/foo
-rw-r--r-- 1 root systemd-journal 0 Jan 25 03:50 /tmp/foo

The contents of /etc/nsswitch.conf are:

passwd:         files systemd sss
group:          files systemd sss
shadow:         files systemd sss
gshadow:        files systemd

hosts:          files dns
networks:       files

protocols:      db files
services:       db files sss
ethers:         db files
rpc:            db files

netgroup:       nis sss
sudoers: files  sss
automount:  sss

How can I reset things so that I can re-create (or change the gid of) the docker group?