If you share access with your media to anyone you’d consider even remotely non-technical, do not drop Jellyfin in their laps.
The clients aren’t nearly as good as plex, they’re not as universally supported as plex, and the whole thing just has the needs-another-year-or-two-of-polish vibes.
And before the pitchfork crowd shows up, I’m using Jellyfin exclusively, but I also don’t have people using it who can’t figure out why half the episodes in a tv season pick a different language, or why the subtitles are somtimes english, and sometimes german, or why some videos occasionally don’t have proper audio (l and r are swapped) and how to take care of all of those things.
I’d also agree your thought that docker is the right approach to go: you don’t need docker swarm, or kubernetes, or whatever other nonsense for your personal plex install, unless you want to learn those technologies.
Install a base debian via netinstall, install docker, install plex, done.
I don’t disagree, but if it’s a case where the janky file problem ONLY appears in Jellyfin but not Plex, then, well, jank or not, that’s still Jellyfin doing something weird.
No reason why Jellyfin would decide the French audio track should be played every 3rd episode, or that it should just pick a random subtitle track when Plex isn’t doing it on exactly the same files.