Anime and .ass subtitles are a bit funky but that’s not due to jellyfin but the player used while streaming in direct play. (In my case)

I had the issue where on my mobile/laptop some subtitles just disappeared or where strangely formated. After some digging arround I found out that VLC was the culprit and changing the default player to MPV or alternatives like Findroid (which uses MPV as default player) everything went butter smooth in direct play !

No idea about transcoding though :/