What to do about security deposit when stainless steel appliances discolored?

[Suzanne Player]

Tenant just moved out, cleaners found they used the wrong type of cleaning product on the stainless steel appliances, causing a permanent discoloration.  Professional cleaners (Molly Maid Company) says it can't be cleaned.

Has anyone had experience with damage that can't be fixed, but maybe doesn't warrant a brand new appliance?

How would you handle this in the security deposit?

Photos below