The reason is that the seller hasn’t shipped the product because they have run out of it or some mistakes with the tracking number occurred. The seller can cancel the order. In this case AliExpress administration will close the order and you will automatically get a refund. It hardly takes more than 20 days.
in this case you contact support, then you can open a Expedited dispute. meaning you can open one within 24 hours. Let HIM cancel it. It's bad for the "reputation" of the one who cancels it, and that's for a reason. It's a way for Aliexpress to weed out the bad practices like "serial cancellers".
Ayt7W.