Hi, when I attach an external monitor to my laptop's HDMI port the monitor is recognised but both the laptop and external screen go blank with only the mouse cursor functioning.

kwin_x11 is using 100% cpu and when i kill -9 it, kwin restarts and everything works fine (until the HDMI cable is removed and re-inserted).

This is with Debian 12 (testing) and I've got a Lenovo P1 with Intel/ Nvidia graphics (nouveau driver). I believe the HDMI ports are hard-wired to the discrete GPU.

Here is a debug file and system information. System info when the monitor is working correctly after killing kwin_x11.