I have one of those lists! It's
this one! And that shows the problem: anyone can make up anything about any UTXO.
Oh my god, this explains my following point perfectly! But I will post it anyway, because I have written it already.
Like I said, if someone pays you in BTC that is on some of these lists, and you pay to someone, then this someone puts it on Coinbase (most likely, most mainstream exchange) to sell, and this person gets asked where this money came from, this person will point to you. So yes, this is a huge problem when it comes to fungibility.
No, this isn't a huge problem. Let me ask the obvious question. You say "this person will point to you". Who is this "you"? How will they know it's you?
Let me draw the picture again:
1. takuma sato gets paid 1 BTC.
2. takuma sato sends this 1 BTC to me (apogio).
3. apogio goes to a KYC exchange and deposit this 1 BTC (don't ask why, I just make it more difficult to prove that the scenario is invalid).
4. the KYC asks apogio (the real person behind the persona apogio), where did you get it?
5. apogio says: "I received it from someone with this address bc1q....".
6. then, the authorities (the most strict ones that you can imagine) search on google the address.
7. they (somehow) find that it is linked to a persona called "takuma sato".
8. they search in the forum for other posts and they make sure that "takuma sato" owns this address.
9. then?
Trust me, I am the one who will have a problem. I will be the one to answer the questions for having this Bitcoin. I will face the consequences for deciding to use a KYC exchange. That's all.
Notice, that in this scenario, I didn't add any protection measures from your side, just to make it more clear.
If between steps (1) and (2), takuma sato decided to do some coinjoins, or to just simply add one more address in the route, by sending to address B and then to apogio, then the authorities would have to search who this address B belongs to, before going back to "takuma sato's" address.