Tonemapping works good. Has worked good since last October.
I showed an example over here: Ubuntu 24.04 & HW transcoding - #160 by Menel
4 hdr tonemaps, on an old 7400t cpu and arc a310.
Your claims don’t match:
Plex isn’t able to support QSV on the Arc like Jellyfin has for over a year
Jellyfin on my test setup (Ubuntu 24.04, kernel 6.8, Intel Arc GPU).
These configuration haven’t been around for over a year.
