I have used "Limited" in Kodi video system setting in the past, with the LibreELEC 11 Beta1 I am getting washed out colors with that setting.
Switching to "Full" seems to crush blacks on first sights.
I am using an Asrock J3455-ITX (Apollo Lake) and my TV is not capable of displaying Full RGB.
Found a workaround to enable full range RGB on GBM using proptest in autostart.sh after searching this and Kodi.tv forum.
Now video levels are back to normal for me.