For many years the Plasma Wayland session suffered from issues with monitor standby breaking things, which has been the one explicit reason why I still need to use the X11 session. In the past the problem was the session crashing whenever the screen went into power saving, typically Plasmashell or Kwin or the screen locker. Allegedly this was because Wayland didn't know how to handle being left without any displays: I understand a fake display is now being used which keeps the desktop from freaking out. I tried this again under Plasma 5.24.3, and for the first time the screen powering off did not appear to crash or break anything.

Unfortunately monitor standby still doesn't work: The screen immediately wakes up as it goes to sleep, instead of staying asleep until I move the mouse or press a button on the keyboard. Since all previous discussion about monitor standby not working in Wayland was related to processes crashing, I wanted to open a new report focusing on the screen not staying powered down. Let us know what's documented on this issue so far, and what extra information you'd like me to provide to better understand it.

It's worth noting that problems with monitors not staying asleep exist with X11 as well: I need to disable the KScreen 2 service from System Settings - Workspace - Startup and Shutdown - Background Services, only then the monitor won't wake up immediately... in Wayland the monitor always wakes up instantly after going to sleep, regardless whether KScreen 2 is stopped or running. I remember that at least with the previous monitor, this wasn't always an issue when using a DVI cable, but both HDMI and DisplayPort would introduce such problems, and yes I tried different cables the last of which are high quality and explicitly the latest version of the interface. All of my video cards are AMD and use the amdgpu module. I believe it was suggested that I look for a setting in the monitor's OSD having to do with automatic source detection, I looked everywhere but couldn't find such an option.

Hello,
just to report that I have exactly the same problem on 5.26.5 on Kubuntu 22.10.

I don't know if it's a Plasma/Wayland bug or an Ubuntu bug. The monitor standby worked fine on other distros running Plasma 5.26.5 and it also works fine on the same Kubuntu installation but on X11.

Moving this to here:

https://discuss.kde.org/t/monitor-insta ... yland/1717

(I also have this problem).