A little hair loss of pure cotton fabric is not a quality problem, but one of the product attributes, which is a normal phenomenon, so don't worry too much. But if you encounter a large area of hair loss, that is another matter. It may be a quality problem at this time. Consumers can find manufacturers to negotiate compensation. After they can't adjust, they can go through legal procedures.
It is normal that the surface of sweaters will appear floating in the production process. Generally, after cleaning, it won't be like this after wearing it several times. If the sweater loses its hair many times, it should be a quality problem, which is generally related to the fabric and production process. When the sweater fabric is inferior, the made clothes are easy to lose hair. When buying sweaters, check the clothes carefully to avoid buying poor quality ones.
In short, it is generally not a quality problem if there is no serious hair loss, but when there is a serious situation, you can find after-sales service at the place where you bought the sweater with the invoice certificate.