This machine used to have a GTX1080 and it worked great but it’s fan was on it’s last legs and I wanted to move away from nVidia so grabbed a 7800XT, backed up everything important and wiped for a fresh install with the new GPU.
Install went fine apart from the ISO not picking up the supported resolutions but figured it was just running an old kernel and the online install should fix that, rebooted into my newly installed system and everything seemed to be working perfect, was a bit jarring not having a GPU tray app but got my head around that and in general the card is absolutely flying except that I can’t shutdown or restart the system without having to press the physical buttons on the case. I’ve looked in the journalctl logs and can’t see any errors for the shutdown at all and when I start a shutdown it is like everything is off, except the lights on the power button and the GPU, also if I press a key on the keyboard that comes back to life.
Has the firmware for that card made it into linux-firmware yet? You might see if temporarily switching to linux-firmware-git from the AUR makes any difference.
Gave that a try but it made no change, I had to skip the gpg signatures of linux-firmware-git by running yay linux-firmware-git --mflags --skippgpcheck to get makepkg to skip the checks, use at your own risk.
Here’s updated last boot logs in case they point to anything;