I have an issue of the display constantly turning on and off during a call with the phone on the side of my face. It is opening apps and once I have had a constant DTMF tone come blaring through. It has even turned on the speaker phone and muted the call.
I have had some people suggest this is related to the proximity sensor moving around or possible screws missing for holding the screen on the phone.
I have purchased a Bluetooth headset to get around this issue.
I am still using Android 8.