That docker version is a bit dated but still OK I guess. I am currently on 24.0.2
Have you tried to pin down the largest consumer of disk space?
du -a /var | sort -n -r | head -n 10
Gives you the 10 top consumers in /var
It also seems that you are using lvm, maybe the snapshots are eating up something, too?
why do you have “docker-compose” AND “docker compose”?
Why did you install the plugin variant when docker compose is already working?
And which one did you use to deploy mailcow? You will get chaotic outcome if you mix the 2.