its not as bad but then when I hit the screen to focus it goes darker.
It might depend on what you're focusing on. When you're someplace that has a big difference in contrast it can throw off your camera. If you focus on something bright, it will make everything else darker, and if you focus on something dark, everything else will get lighter. For example, I'm in my room, it's the middle of the day. If I focus on my window with the sun coming directly in, everything else gets really dark. If I focus on the wall, everything else gets lighter.
Here's an example (if these turn out super big I apologize in advance, I don't know how to resize them haha) :
The first one was focusing on the window, and the second was the wall. (I know these aren't very good pictures, it was just to show the effect. And I didn't have to move at all to take them.)
Edit: Also, to your first post, I tried putting mine on full brightness and then going into the camera. It does get a little darker, but not much. I'm pretty sure that's just how it is. I think the reasoning is that when you have the phone in full brightness, it can get warm if you do some intensive things like game or just having it on nonstop for long periods of time, so they lower the brightness on purpose when you hit the camera so it doesn't heat up from full brightness, plus having the camera open, plus having a real time view of the cameras. You could probably test this just by shooting a long movie and then feeling how warm it is to see what I mean.