I was able to get twelve 4K HDR (DV7.6) tone mapped transcodes going simultaneously on my A380. With transcode throttling I could probably juggle a couple more.
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