Out of curiosity, are you running the ps command in the container or on the host? Just realized that its only showing the actual jellyfin process and not whatever ffmpeg command was consuming 9.8GB of memory.
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