I have been using MEXC for a while now and when I log in it says that I should do a KYC before I do spot or future trading. There is no clear answer to questions in the chat.
But what also surprised me is that Kucoin is specified as the sender for transactions. Could it be that MEXC is a subsidiary of Kucoin and is now also subject to regulation?
Do you know anything else besides Poloniex? I will definitely test it but the no KYC exchanges are disappearing more and more.
You could try HTX, their level 1 KYC only ask your country, your name and your birthday, you can withdraw up to 5BTC/24 hours.
It's strange that MEXC ask you to complete KYC before you trade, why you not try to use wallet that has built-in exchange like SafePal? I've successfully trade multiple times without need to submit KYC.