What operating system is Jellyfin installed on? And what install method? Most install methods will preserve your existing install. Only a mis-configured Docker install will lose data.
Jellyfin 10.10.6 (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