Just been out and checked mine and I have the same problem more so on the drivers side but not on the outside edge only on the inner edge were the paint has worn off!
Further more it seems the problem is the plastic wheel arch liner (combined with muck, grit ect) rubbing the paint off the inside of the wing thus rusting through the panel over time, you can see this with a torch and mirror. So I would say it’s a design flaw that needs addressing and maybe trimming the wheel arch liner so it can’t rub the wing?