buttons disappear in video call

Sometimes when I'm in a video call and get my finger close to the screen it makes the buttons (hang up, mute, deafen, turn camera on/off) disappear. It's really inconvenient and frustrating because usually when I move my finger close to the screen it's because I want to tap one of those buttons.  

I'm not really sure what the purpose of that is (I guess to reduce extra stuff on the screen in video calls) but whatever it is it has the side effect of making it unreasonably difficult to quickly adjust things. So I guess you need to work on fine-tuning that. 

I use an Android device (not sure if that matters).