You can remove it
sudo apt remove --purge linux-headers-5.8.0-63-generic linux-modules-5.8.0-63-generic linux-modules-extra-5.8.0-63-generic linux-image-5.8.0-63-generic
just to clear it out.
Hmmm... Both the 5.8 LTS and the current 5.13... No good.
You might test the Liquorix patched kernel just for certainty... But at that point, it raises doubt as to whether the kernel is the actual issue.
Which is problematic, since the AMD Drivers are included in the kernel.
If it is the AMD graphics and not the kernel... then that implies something wrong with the card.
You also could try installing the proprietary AMD Drivers from the AMD website to see if there is any difference.
If that makes none and the kernel hasn't... I would definitely be checking the integrity of that graphics card at that point.