Screen is really dark and wasn't before.

So this morning I'm playing ghosts of tsushima. I go to work and when I get home turn all my stuff on. My screen is dark my letters are black. Eventually I found a theme that let me see a little better. I loaded up ghosts and it activated HDR (I have a pro and 4k tv) and it looks great. But when I close the app it goes back to almost pitch black. Help