This problem may occur after hand washing without using a washing machine and directly drying by hand, regardless of what detergent you use. Of course, it is best to use special detergent for down. Just hand washing is to clean the residue in down, and it is best to shake it with a washing machine and clean it again. The drying time should not be too long, not exceeding 1 min. Don't worry, slimming is not a thin chest.

Besides, it seems that bleach can't be used in down jackets. ...