It's called "tainted Bitcoin". Basically, you can get a list of all transactions a coin was involved in since it was minted. If any of those transactions contain a blacklisted address, exchanges would refuse the token.

> I'd love to learn more about this,

It's worse than this.

Coinbase, for example, will close your account if you use you Bitcoins for things they don't approve of AFTER you withdraw them.

This is... remarkable. Many cryptocurrency advocates have promoted bitcoin by making exaggerated claims regarding fiat currency's centralized control and lack of privacy. Now bitcoin itself exhibits the very characteristics that were often claimed about fiat currency, except it's not an exaggeration.

Easy solution don't use Coinbase. It's not the end of the world.

> Easy solution don't use Coinbase

I most certainly don't.

But the hordes of clueless users who continue to flock to the platform are blissfully ignorant of that fact.

Worse, the fact that coinbase is behaving in a way that's completely violating the spirit of Bitcoin while profiting from it doesn't solve the problem that what they are doing is possible because of a severe limitation of the platform.

I am a big and very long time fan of Bitcoin, but the traceability / fungibility issue has bugged me from day one.

I really wish the dev. community would focus on introducing a fork with an technical solution to this problem instead of polishing the turd with minor stuff no one really cares about like taproot.

Here's a relevant episode of the ZK Podcast about cryptocurrency mixers: https://zeroknowledge.fm/111-2/

Look up AML regulations in your jurisdiction. They typically have a transaction risk level and I assume somehow the anonymity ups that risk.