have this problem since 5700 XT was released on almost all driver versions (some may have fixed it but don't recall versions). So now I'm on latest Adrenalin version and problem persists (just like on all recent driver versions).
Reproduction: Starting game (Rocket League or Destiny2) with Freesync enabled makes the monitor lose signal for 2 seconds every 2 seconds so basically itz just flickering between game screen and blackscreen. This happens in fullscreen and windowed borderless fullscreen. This doesn't happen in smaller windowed mode just exclusively in any full screen settings. This problem immediately stops after turning off Freesync. My second monitor an AOC with 240hz doesn't have this issue at all.
Workarround: Launching game watching it flicker, get mad, tab out to second monitor and switch affected monitor in radeon settings from 8bpc color depth to 6 bpc and then to 8bpc again while the game is launched (just switching one time already fixes it since the monitor kinda gets reset by changing this but I guess 8bpc is better). This fixes it until the next time the game is launched (I'm not sure but it could be that the problem is fixed for as long as the pc stays active but shows up again after pc was restarted or in sleep mode). Disconnecting the monitor while the game is open and reconnecting sometimes fixes it too.
Please for the love of god this issue persits since launch day of the 5700 series, HALP!