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.
Use more detergent. Parts that are already discolored will not revert to their original color.
For thorough and gentle cleaning of glasses, dishware, and cutlery, Miele recommends using Miele products.
