IOS 15 - screen black but backlight is on

Not sure why but my iPhone 7 with iOS15 randomly but partially lights up.

At night it’s charging on either DND or sleep but when ever a notification comes in it turns on the screens backlight. I am still able to use the phone I hit either the unlock button or the home button and it lights up like normal.

yes I have disabled rise to wake and silenced notifications show on Lock Screen.