I’m afraid you are running into the issue described in Coastal Explorer on iPad Flashes and Loops Endlessly - #2 by rcassano. It turns out this is caused by a bug in iOS/iPadOS version 15 and we are waiting for Apple to release a fix. Unfortunately they have not provided us with a timeline for that fix and we have been unable to come up with a work-around.
This problem does not happen everywhere, but it does seem to be common in the Chesapeake Bay area as well as some others. Since that’s where you are, and we can’t say when Coastal Explorer will work there again, you might want to request a refund from Apple. Instructions for requesting a refund can be found at: Request a refund for apps or content that you bought from Apple - Apple Support.