Your item was declared non-compliant? At least one element didn't match with the description in your listing.
For example :
A bag is labelled as being in "Very good condition". If the item shows signs of wear, scratch marks or spots, quality control won't be able to validate it as conformed. Vestiaire Collective is then obliged to cancel the sale and refund the buyer.
Any non-conformed item will be sent back to the sender's billing address. Furthermore, it will impact your "recommended seller" percentage, and could even lead to losing your "recommended seller" status.
Any counterfeit item will be declared non-conformed.