1/2 inch line on either side of back up screen suddenly appeared after 14370 miles. Dealer says it was like this when you bought it.
Ask to see one on the lot that does the same thing.
You can use any dealer for warranty problems and in your manual there will contact info for corporate .
You don’t even have to drive the minivan on the dealers lot. Just start it up and put it in reverse.
So it was broken when you bought it! Still under warranty, dealer must fix it.