I just started playing the game (I'm still in Cyseal). I was going around town when all of sudden out of nowhere my screen turned black. I could still hear sound from the game but I couldn't do anything. After 2 minutes or so the screen suddenly turned back to normal, and I proceeded to close the game (did not want to risk having the issue occuring again, thinking it was better to just close and re-open the game).
In case I will encounter this issue again I decided to post here and try to find out if this is a known issue and if there is a fix.

Thanks for the quick reply.
I don't think it's a GPU drivers problem since my drivers are up to date and the game ran fine the rest of the time.
It happened when I tried leaving Cyseal (without even knowing it) relatively early even before gathering additional companions and such, so maybe thats what triggered it. So far this issue didn't occur again.

Late Edit: I already finished the game some time ago so it's no longer relevant for me but just wanted to update that the issue is indeed most likely related to AMD GPU Drivers/Hardware (and even though at the time my drivers were up-to-date it didn't help) and probably isn't connected to the game itself. From what I gather it's a known issue that makes the screen randomly go into Power Saving Mode loop. Not sure about a solid proper fix from AMD though, it's possible that at the time of this edit things are better in terms of their Drivers.