I am running KDE/Plasma (latest 5.26.5) on Arch/Linux with a HiRes display (4k) in a Wayland session.
Insync (3.8.4.50481) does start and run, but the application window is completely broken:
- half the size in both x and y dimension
- mouse input reacts to clicks in larger window but shown in smaller window (that is, clicking on the assumed place of the three dots in the larger window will show the menu in the smaller - see attached screenshot)