Okay, i think it's a mesa and/or marco related bug.
Without the ppa and Kernel 5.4.0-58-generic i had to deactivate Adaptive composit of marco.
See this Bug:
Then I started Prominence Poker and it freezes with a black screen, but the system isn't effected.
Will try the ppa with disabled adaptive composit of marco.
I expect a black screen of prominence poker aswell but i don't think the whole system will crash.