Can't be of much help, but
I get this error with the official Android app only.
But if I use an other app like Fladder or Jelliflix... it works. FireTv Android app and Web is working too.
I have mostly the same scenario as you. (proxmox) LXC Container with iGPU passthrough (AMD) on ubuntu 22.04 container (upgraded to 24.04 with Jellyfin 10.11.0 from 10.10.7).
Would be nice to know if you use the Android App too
I get this error with the official Android app only.
But if I use an other app like Fladder or Jelliflix... it works. FireTv Android app and Web is working too.
I have mostly the same scenario as you. (proxmox) LXC Container with iGPU passthrough (AMD) on ubuntu 22.04 container (upgraded to 24.04 with Jellyfin 10.11.0 from 10.10.7).
Would be nice to know if you use the Android App too