After I updated my iPad to iOS 15 I have had the same nonstop flashing and looping as well. Thought it was just me. I tried restarting the iPad but this did not resolve the issue.
Update: I tried deleting CE iPad and downloading a fresh copy. After signing into my account I was not able to get the app to center on my current position and stay there. It continued to jump back to the Seattle area, (Lake Washington area).