The black screen flickering occurs during games in freesync mode on my Benq EX3203R Freesync 2 monitor.
I'm also currently on a Asus strix radeon rx vega 64 and kubuntu 19.04 with mainline kernel 5.1-rc3 and oibaf ppa mesa drivers with appropriate settings. The VRR feature does work, it just gets black screens every 3 seconds or when i move in game. This does not happen on windows 10.
Any news on this topic is appreciated.