Found this, which helped a lot:
https://nerdschalk.com/garmin-app-crashing/#:~:text=Change%20Apple%20Health%20setting%20(For%20iOS%20users),-Open%20the%20Apple&text=Tap%20on%20%27Connect%27.&text=Proceed%20to%20disconnect%20and%20reconnect,fix%20the%20issue…