Hi,
I have downgraded now the firmware manually to the old one. Im not sure what arch is doing, but ive suggested them to revert all amdgpu commits.
The crazy thing: This was over a week in arch testing and barely complains.
Its now fixed on CachyOS side with following firmware:
linux-firmware-1:20250508.788aadc8-1-any.pkg.tar.zst
Should be available in a few minutes automatically via sudo pacman -Syu