Oh, it seems I totally forgot to add that it is an Nvidia RTX 4080 (fixed that). And the drivers are the latest in the Arch repos. But it happened with previous versions too. The monitors are connected via Display cable, and switching / reseating those was one of the first things I tried. If it is a hardware failure, wouldn’t it happen all the time, or at least not under so specific circumstances? I play other games like Red Dead Redemption 2 that similarly tax my GPU, but never noticed anything like this.

Since you want an arch based dostro, i can highly recommend EndevourOS. Its comes with an easy to use installer, many desktop env options and a few quality of life tools like a comandline tool (nvidia-inst) to install nvidia drivers. And if you choose KDE Plasma in the installer, it will default to wayland.

AMD is still by far the better gpu choice for linux, but since explicit sync support is now in the 555 nvidia driver and kde plasma 6.1, most problems that nvidia had (i had) with wayland have seemingly just vanished. So no need to imeadiatly buy a new gpu.