The basket of the Xiaomi Smart Air Fryer 4.5L is made of cold-rolled plate, not stainless steel, and the internal structure of the basket is not completely sealed. If acidic or alkaline solvents are used for cleaning, the moisture in the solvent may remain on the side walls of the screw holes, causing water rust and scale, which is normal. It is recommended that you wipe off any remaining moisture with a soft cloth after cleaning. The pot body of this product is made of food-grade material. Even if there are these marks, it will not affect normal use, so you can rest assured.