Nothing is missing per se, but mysteriously 100% of my friends prefer the Plex UI. I'd have to ask them why. I find the jellyfin UI a little bare but serviceable, my only real complaint is the mysterious transcoder errors.

And I'm sure it is just a misconfiguration! The problem is I hardly changed any settings from stock, aside from enabling hardware transcoding for Intel quick sync. I have an Intel Nuc10i7FNK that has a comet lake i7-10710U so based on the table on Wikipedia which lists which generations of quick sync support what codecs, I set Jellyfin's hardware acceleration to QSV with QSV device set to blank (it works and I can see the activity using the Intel quick sync top command - I forget what the command is but I verified it when I set it up so it seems it's auto detecting it fine), and enabled H264, HEVC, Mpeg2, VC1, VP8, VP9, HEVC 10bit, and VP9 10 bit. Leaving 12 bit and all of AV1 deselected which seems to match what isn't available for decode according to the Wikipedia article. I left low power HW encoder off and enabled VPP with gain 28 and contrast gain 1, regular tone mapping disabled, tone mapping algorithm the default of bt.2390 and all the other settings left on default.

I know jellyfin is working on auto detecting the hardware acceleration settings so I don't hold it against them at all. I should also mention that the file that wouldn't play before plays fine now, so it doesn't seem like there's a specific file that causes issues but an intermittent issue that causes transcoder errors. The file that wouldn't play before is just 8bit HEVC with aac2.0 and English srt subs.

I welcome any tips you have - one issue I have when looking for help with Jellyfin is that people see users asking for help as a challenge to "prove them wrong", which is frustrating (and ironically sometimes how people approach proselytizing the fediverse). I genuinely want Jellyfin to be good and to use it, which is why I keep an updated jellyfin container running along side my Plex container, I have basically every jellyfin app installed on all my devices so I can keep up with their development, and I donate to developers of those apps even though they aren't complete enough to use in the case of Findroid. I would have already opened an issue for jellyfin web if it was easy to reproduce, but like I said I haven't had much time to troubleshoot between job and working on the arrstack so this is all the details I have right now.