I didn't know that some DEX's have KYC verification? Are you sure about that or I just wasn't aware of it?
They don't. If the exchange is truly decentralized like Bisq, then there will be no KYC and indeed there will be no centralized entity which can even collect KYC information. The problem is that many exchanges uses the word "decentralized" as little more than a marketing gimmick despite being nothing of the sort. IDEX which OP has quoted is the prime example of this. It isn't decentralized in the slightest.
I think you are being redundant and inconsistent with your topic. Previously you said it requires KYC, then now, KYC is not involved?
OP clearly has no idea what he is talking about and is just trying to shill his "exchange building site", which is a cookie cutter scam site and completely plagiarized from elsewhere.