I’m experiencing this odd issue on Wayland, not on X11.
Basically, if I’m running Krfb and turn off my PC’s monitor in the meanwhile, the display appears to “freeze” in place on the client’s side. I can still connect like it’s actually working and I can move around the mouse, but I can’t interact with anything and the display appears to just stay stuck. Restarting Krfb doesn’t help, only rebooting does.
This makes Krfb entirely useless, as I use it for accessing my PC when I’m not in the same room (in which case I always turn off my monitor).