1. It may be that the merchant is taking off the goods and putting them back on the shelves.
2. The goods in this store are sold out because of their few varieties and high popularity, so they are all off the shelves.
It is also possible that the goods in this store have been complained, and all of them have been removed from the shelves in order not to cause adverse effects.
It may be that the store can't do it anymore, so the goods are off the shelf.