Not sure if its XWayland but the vision stutters a lot while everything else is smooth. Also X11 seems unusable for some reason on KDE because I get a lot of glitchy artifacts (and Direct Mode seems to be enabled)
Edit: Using an AMD 6750xt with i5-8600k on Arch Linux with KDE Wayland
Did you disable async reprojection by adding
"enableLinuxVulkanAsync" : false
into yoursteamvr.vrsettings
config file?I play a lot of Half-Life Alyx on my Index and it works pretty well.