Once it starts it just keeps getting worse. I sanded, cleaned, primed and painted these spots on mine just to see what happens before I got a new paint job. Yesterday I was going to repair another spot on a different door and took the air hose to blow off the dust from sanding and about a 10” spot of paint came off the door. It peels off like the paint isn’t even sticking to the truck. Can’t believe GM has never taken responsibility for these paint jobs.