SUMMARY

The org.freedesktop.ScreenSaver SimulateUserActivity dbus method is supposed to reset screen blanking timeouts. It works for both the screen locker and the Screen Energy Saving feature when used in X.Org desktop sessions. However, in XWayland sessions, it works only for the screen locker: The Screen Energy Saving feature ignores SimulateUserActivity on XWayland, and the screen therefore powers off when it should not.

STEPS TO REPRODUCE
1. Start a KDE Plasma 5 XWayland desktop session. (I used KUbuntu 21.04 in my test.)
2. In KDE Settings: Screen Energy Saving, enable the feature and set "Switch off after" to 1 minute. (Note: You might need real hardware, not a VM, for the option to appear.)
3. Start a shell script that runs the following command every few seconds:
   qdbus org.freedesktop.ScreenSaver /ScreenSaver SimulateUserActivity
4. Sit back for a minute waiting for the energy saving mode to activate.

OBSERVED RESULT

The screen powers off, ignoring the SimulateUserActivity calls. 

EXPECTED RESULT

The screen should not power off. It should respect the SimulateUserActivity calls, just as it does in an X.Org session.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 21.04
KDE Plasma Version:  5.21.4
KDE Frameworks Version: 5.80.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Problem exists with XWayland sessions, but not X11 sessions.