I was on 2019.20.4.2. I don't think it was bad cell service. I tried this a few different times on the trip in different areas, and got the same result. Each time it would happen after 5 to 10 minutes of having tesla waze up on the browser. Once when my wife was driving, it even flashed up an alert on the center screen that took up the whole screen, with the red hands on the wheel. This same alert did not appear on the instrument cluster, just affected the center screen. Quitting tesla waze instantly cleared everything up, so I don't think a reboot was needed.
I wonder if having tesla waze up and constantly updating on the screen is too taxing on the MCU when autopilot is also working?