N1534141565261 , via OnePlus 7 Pro , Nov 21, 2020 : My 7 pro locks while I'm on video call from facebook Messenger. The front camera also closes. This happens every 30 secs or in a minute. I have to keep touching my phone to prevent this from happening. This only happens with the Messenger app. First, the screen loses brightness and then the phone locks after some time.