Maybe related (based on the above log extract):
Consistent screen freezes after upgrading to F42 → mostly the later posts (earlier a few different issues accidentally came together in this topic)
There are further related topics, I already mentioned them in the other one.
If it is the same issue, it is likely solved soon. 6.15 gives hope, but also 6.14.9 contains related fixes and so far seems to solve the issue for several people who tried it. For more, see other topic and the two AMD issue tickets mentioned there. There is also a mitigation that works for most, just in case 6.14.9 does not yet fix the issue. Again, see the posts in the other topic and the AMD tickets 