I am still having this issue where the display goes into spasm and makes the system completely unusable. I think i've tried every 5.12 kernel, and the 5.13rc3 one, all same result.
Booting from the Live garuda-dr460nized-gaming-linux-zen-210507 is also the same result, so It can't be me.
It’s kind of an old bug at this point from a couple weeks ago back from 5.12.1, the latest is up to 5.12.6. Maybe it was fixed on May 14th and whatever it is could have broken again in development process.
Sounds like the problem is solved though. If you’d like you can open another Bug request on Arch, but there’s not really anything we can do here to help you.