I may have the same problem with a Gigabyte 32" monitor on a Vega 64.
My black screen is a 2-3 sec duration roughly once an hour
2560x1440 165Hz Displayport.
120Hz on Displayport helps a lot, but does not fix the problem completely.
144Hz HDMI looks like it is working, but have only tested a couple of hours.
Tried 3 different AMD drivers and 2 different screen firmwares and a bucket load of windows updates.
Bought a 8k rated Displayport cable, no difference.
Initially though my screen was defective, so it is now send for warranty repair, but reading the Samsung G7 manual says the following: "― If you change the screen resolution while the function is On, the screen may intermittently blank out due to
the graphic card. Set FreeSync to Off and change the resolution."
Samsungs chat statement is that this problem is a AMD Freesync problem and not a Samsung screen problem.
I apologize if this is not the same problem.