I'm running Manjaro KDE edition on my MS Surface Book, and I decided today to install the plasma-wayland-session package and give Wayland a shot, as it is supposed to have a better touchscreen implementation. The 3000x2000 resolution of this display requires a scaling value of 200%.

I'm having an issue with Window Decorations. I thought at first that they weren't rendering at all, but I can see the window borders in the lower left hand corner of each window filling exactly half of the height and width of the window, indicating these elements are ignoring my scaling setting and rendering at 100% scale. Setting the scale to 100% causes the borders to display normally (albeit with everything too small), but if I increase scaling above 100% the borders continue to render at 100% and are effectivel hidden behind the properly-scaled window.

I've tinkered around with the display settings and tried different resolutions and themes with no luck. Does anyone have any idea where I might start troubleshooting this? Note that I am currently running kwinft, but had the same issue in standard kwin.

Screenshot of the issue
https://imgur.com/a/62oNViP

Follow-Up:

Leaving scaling at 100% and doubling font DPI to 192 resolves the window border issue and solves some other problems with low-res fonts that I was seeing, but that causes icons in certain applications to appear too small, such as in the KDE Settings pane, dolphin sidebar, and right-click menus.