I run my Joplin server through portainer/docker on my NAS. I thought to check for updates, and noticed last version is 2.7.4 from 4 months ago on docker hub, while the latest release on github is 2.8.8 at the moment if I see correctly? Are docker images not provided anymore for some reason? Or aren't releases after 2.7.4 stable yet perhaps?
It looks like there have been same changes to the server since then, so I would expect a release to come up once ready. In general the server doesn't update as often as the desktop app, so the github isn't a good place to check for updates, dockerhub is better.