We found there seem different standards (qualities) of stainless regardless of nomenclature. A pair of mid-priced bins from Bunnings kept in a bathroom and ensuite after a few years began to corrode exactly like your fridge. When they got too ugly they were replaced with better quality products and no worries near a decade on.
The 20 year old Amana fridge has no trace of corrosion but the 8 year old Siemens dishwasher has a few small spots developing on the door. Products such as Magic Cleaner go a l.o.n.g way as not much is needed per use and helps the cosmetic appearance and seems to create a protective barrier.
‘Polishing’ the corrosion with crumpled Al foil or Al foil and dilute vinegar might remove the corrosion but try it in an obscure spot first to assure it doesn’t scratch or make it worse.
