Your other option is to configure Jellyfin to write logs to a non-standard directory and that directory is a mapped volume on both nginx and jellyfin. Or symlinks.
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