With fast fashion, it's often just cheaper to throw it out then go through even the most basic of QC steps to ensure the product is still in sellable condition.
The fact that it is fast fashion is the issue. No labor cost since it's made by slaves. No material cost since it's basically sewn together with hopes and wishes. All you really pay for is the shipping.
If that garment you want to buy is cheap, odds are it's made with blood and paid for with climate change.