DIAGNOSIS That's damaged non-stick coating. It's not safe to cook with if it's flaking into your food, and it's often caused by using metal utensils, abrasive scrubbers, or harsh dishwasher detergents.
FIX Stop using it immediately. Contact Cosori customer support directly with clear photos of the damage. This is a known issue with some batches, and they are typically very responsive, often sending a replacement basket under warranty.
IF THAT DIDN'T WORK If they don't provide a replacement, you can purchase an official Cosori-branded replacement basket online. Do not use a generic one, as the fit and safety may be compromised.
HEADS UP To preserve the new coating, hand-wash with a soft sponge and mild detergent. Never use steel wool or put it in a dishwasher, even if it says it's dishwasher-safe—the harsh chemicals and heat accelerate wear.