I have the same problem and there is a solution. With nvidia on my laptop, it seems that with kde there’s some DPI problems
add this option in your /etc/X11/xorg.conf on the “Device” or “Screen” section ;
Option “DPI” “96 x 96”
if you don’t have a xorg.conf, generate it via sudo nvidia-xconfig
Wayland doesn’t work for me with KDE-Nvidia, it’s not really ready yet, stick with x11 for now