I have thought it could be the game, even if it would be a terrible coincidence that it starts replicating the exact issue I’ve had before outside of it. I’ve also been playing the game just a couple of days earlier for hours on end with absolutely no issue. Also tried searching for anyone having the same problem with the game, but only found other black screen issues, like the black screen on start you mentioned, which are all more obviously software/driver related. But this is genuinely the whole PC crashing. I mean, it cuts power to my keyboard, my controller disconnects.
I should probably also try expanding my testing grounds, see if any other games run fine or crash too.