I found this

Black or Grey Residue on New Stainless Steel

What is the black residue on new stainless steel cookware?

When SS cookware is made, a mechanical polishing process using very fine abrasives is used to make it shiny. Sometimes this process leaves a residue that cannot be removed by hand or dishwashing.

Here’s what KitchenAid recommends: spread a small amount of olive oil on the inside of the pan. Let it sit and then wipe the oil out. After that, proceed to wash with dish soap and hot water.

Other recommendations are to gently scrub using a mixture of lemon juice and salt and then wash.

It's not rust, because I can't see in your pics a hint of the telltale orangey color of rust. I would call Kraus, and also try what @Sherry Brighton says above.

WD40. I made a sink look terriffic with it today.