Australia currently bans the sale of "recycling" plastic and e-waste to certain countries in South East Asia because of this problem (dumping to companies that have no qualms about throwing the waste into waterways etc)

The waste is still making its way to those countries, and the way that we know is that NGOs are tracking it[0]

I suspect that clothing will get similar treatment - initial illegal dumping as you predict, followed by determined NGOs holding the supply chain to account.

[0] https://www.abc.net.au/news/2026-01-30/gps-in-e-waste-from-a...