> How would you concretely ban such a thing?

Uhmmm, so your answer is to have to some group of people asses every item of clothing or every new brand that pops up to see if it qualifies as fast-fashion based on whether it was influenced by recent catwalk trends or whether the factory it was produced in made it too fast or efficiently. ? yikes. Not sure if you realize that just how subjective and unscalable that is.

They do PDO for food, how hard would it be to do something similar for clothing? This that and the other brand qualify and get some random inspections, this other MFG doesn't meet criteria and gets banned, there you have it.

You’re describing central planning, not PDO (which is labeling requirement).