Hey Dave, glad you brought this up because I have the answer for ya! We had the same thing happen! You need to stop using that detergent immediately. That gel contains HYPOCHLIRITE! Chlorine! Chlorine and stainless steel do not mix. It will begin destroying the stainless and staining it white. My parents had this happen to their older Maytag with a stainless interior, below the dispenser all the way down the door into the floor of the tub was stained white from the cascade original gel which contains chlorine and also the same brand you said you and your mom use. If she likes gel, I highly suggest cascade Complete. It uses enzymes instead of chlorine and is safe on stainless interiors. Considering the vast majority of Americans have stainless interior dishwashers, you would think they would put a warning on the label but nope you gotta find out for yourself unfortunately but hopefully you see this so she doesn’t end up destroying a brand new machines interior. Throw that stuff out or use it with a white plastic interior dishwasher.
If she has soft treated water conditions, gel and powder with rinse aid is enough. Pacs are extremely concentrated like Cascade Platinum, Complete and their original pacs. It’s overboard for most water type situations. I’ve had a ton of oversudsing from cascade platinum, neither the original or complete pac does this only the platinum I’ve found will oversuds. But if you’d like pacs they will be safe as none of them contain chlorine going brand to brand.