[ sudo nano /etc/default/grub ] or sudo with your favorite text editor
Go to the end of the first CMD line. After splash type " radeon.si_support=0 radeon.cik_support=0 amdgpu.si_support=1 amdgpu.cik_support=1 modprobe.blacklist=radeon " and press control+x, then press Y & Enter to save and exit.
Now update grub.
[ sudo update-grub2 ]
Then just reboot. If your hardware is supported you should be using the new Open Source AMD driver.
This also allows the use of RADV [ mesa-vulkan-drivers ] package in apt.
I have another video on how to use the AMDVLK driver as well " https://www.youtube.com/watch?v=TDGMZCnvuWg " on unsupported GPUs.