/var/lib/jellyfin/transcodes

[fflam]

I cant say why it was working and why now it is having issues.

However in the dashboard -> Scheduled Tasks, there is a Clean Transcode Directory job. It is set by default to run every 24h. you can lower that time and see if it helps.

also there is an option near the bottom of Playback -> Transcoding, called Delete Segments, This deletes the transcode files right after they were sent to the client.

2 options to try