Sorry, I've not been anywhere near clear with my posts, due to only having a few hours in the evenings to test (stealing my wife's monitor and keyboard)so you’re using an image of the full distro with Xorg? Or using the base OS image and then jellyfin via container or running ffmpeg directly?
What is your CPU?
Have you tried the latest mesa from here? These don’t work for me but they also don’t crash the system or cause errors in dmesg.
First i tried a lxc container in proxmox,
then on the proxmox host its self.
New install of Ubuntu 21.10 on bare metal and install jellyfin.
The CPU is 5700G on a ASUS MB
I'll try and give the link a guide Friday (gotta migrate my Home assistant from Ubuntu 18.04, python 3.7, mariadb 10.1 tonight)