Bug filed: https://bugs.kde.org/show_bug.cgi?id=429845
SUMMARY When using KWin on Wayland with an NVIDIA GPU and an OLED monitor connected via DisplayPort, waking my display from shutoff (not sleep or suspend) via USB input (mouse/keyboard) fails. My monitor reports excessive refresh rates (kHz range) and impossible resolutions. The same hardware configuration seems to work correctly in X11.
My only workaround now is to always "wake" my monitor by power button, regardless of system state. This seems to work consistently.
STEPS TO REPRODUCE