I believe Jellyfin was a fork of Emby a number of versions back originally. I’ve used Emby for some while and had no issues other than the occasional case where transcribing some ridiculous bitrate file eats up resources. Streaming to Emby (as in the cast icon) via Roku has an issue with series that have more than 100 episodes on them due to an index size issue, that might have carried over to to Jellyfin?