Not 100% sure, but it look like with "Shein drops up to 10,000 new items on its website daily" (source: https://www.npr.org/2023/10/13/1204983212/shein-america-fast...), it is H&M and Zara on steroids.
The expiration date on clothes is so short that now transporting it by boat is not too slow, and they have to take plane.
(writing this post, while wearing 4yo jeans, and 5yo t-shirt)