The official image jellyfin/jellyfin tracks unstable
Huh? That doesn’t appear to be the case. jellyfin/jellyfin:latest, which is what they tell you to use in the installation instructions. gives me 10.8.13 which appears to be the latest stable release.
There are newer and unstable versions available in dockerhub as well, but latest doesn’t give you those. After all latest is just a tag with no special meaning of itself, it doesn’t necessarly give you the most recent build.