NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
I have i915 as a driver and hence having wide range of colors by default is definitely not for me. In KDE however there's a RGB range option in Display settings applet which, in my case should be manually set to Full (it's Automatic by default, which probably means "whatever driver decides in its wisdom"). The option can also be set by kscreen-doctor:
The option however keeps getting reset to Automatic after rebooting - it doesnt matter if I set it through the applet or kscreen-doctor.
Moreover, if I use libdrm's proptest to set properties of connectors so the option is set even in ttys, after starting KDE, I still get reverted to Automatic on it.
STEPS TO REPRODUCE
1. Have i915 & a screen connected with HDMI
2. Set RGB range to Full in Display settings
Linux/KDE Plasma: Arch, latest
KDE Plasma Version: 5.24.0-1
KDE Frameworks Version: 5.90.0-1
Qt Version: 5.15.2+kde+r297-2
*** This bug has been marked as a duplicate of bug 442520 ***