In the Docker settings, you defined a location on the host file system to mount /config. In that folder there should be a log directory. Can you share the main jellyfin log and one of the FFMPEG logs?
Jellyfin 10.10.7 (Docker)
Ubuntu 24.04.2 LTS w/HWE
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
4x WD Red Pro 6TB CMR in RAIDZ1