I rolled back to OneUI 2.5 with Odin then flashed uk beta 2. There is a post in here with instructions for it, 709 or something like that.
Definitely not working, disabled.hex+ and pro, after applying high contrast 2 and reboot half the theming disspaears, quick settings and notifications are themed, but the core interface, settings, app backgrounds are defaulted.
UPDATE: beta 4 was pulled by Samsung beacuse of a serious bug (source: https://www.sammobile.com/news/fourth-one-ui-3-0-beta-galaxy-s20-series-improves-space-zoom/)
maybe it has to do something with VoWiFi disappeared...
thanks that really helped.
go to settings > apps and select google play services, then 3dot menu > uninstall updates