Natural dyes, e.g. from carrots, tomatoes or ketchup, may be the cause. The amount of detergent used or its bleaching effect was not sufficient to deal with natural dyes.
Increase the quantity of detergent. Parts that are already discoloured will not revert to their original colour.
For thorough and gentle cleaning of glasses, crockery and cutlery, we recommend Miele products which also care for your dishwasher at the same time.
