Random Vibration

It’s kind of complicated to explain but I will be on a FaceTime call (not limited to FaceTime this has also happened while on Google Duo) and my phone will start vibrating but not like a notification, it’s completely different my entire phone will just vibrate uncontrollably, where it even causes the person on the other side of the call to see my screen fuzzy because of the vibrating, and it only stops when I have ended the call and closed the app. This has been going on for a while now because I didn’t think it was a big deal but even after updating my phone it continues to persist