Configured layouts through System Settings, unable to use even simplest shortcuts like ctrl+v while on non-english layout. Works on X session. Using alt+shift for layout switching. Looks like it isn't Qt or Wayland specific since works from Gnome on Wayland. Related to #383113 and #107864 somehow?
Shortcuts like ctrl+v are application shortcuts. This means the issue is in Qt, not in KWin. Given that you write it works on Gnome, I'm relatively certain it also works for GTK applications on Plasma/Wayland.