Comment 19 for bug 1850654

Moreover, the firmware files are missing at the linux-firmware git:
https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/amdgpu

The solution below suggested to copy it from the link above, but I can't.
https://askubuntu.com/a/1124256

I have just now fetched some updates for my Ubuntu 20.04 Focal Fossa LTS, but the issue still persists. I think the issue are missing drivers for some really new Radeon cards in the linux-firmware upstream. My RX550 is using the amdgpu driver apparently (see the listings in my post above) and the graphic performance seems to be alright for watching 4k video. Probably the RX550 is unaffected, but one is unable to use the new Radeon cards.

There are a few strange issues, though. There are no "restricted drivers" listed at the "Software & Updates >> Additional Drivers". This is strange, since the RX550 should be able to use either the open amdgpu or the restricted amdgpu-pro. Also note I seem to have some video quality issues with the VLC (absent in Videos), but it might be a codec issue.