Then you inside the camera app and press "F" . The camera will move down wards a bit but other than that functions of the camera are shown like normal but then you press "ESC" it goes to the main menu instead of closing the camera app.

I guess what happen in this case is that by press "F" the character puts the phone away, like normal than not using but the camera interface remains. That`s why the movement downwards in the app.
The game registers that the phone is not in use and by pressing "ESC" goes to the main menu like then you not using the app.

So the main interface issue is that the camera app should close by pressing "ESC" or "F" in the app or the button "F" should be blocked than using the camera app.