1. Unverified Accounts: Withdrawal limit of 5 BTC per 24 hours
2. Primary KYC Accounts: Withdrawal limit of 80 BTC per 24 hours
3. Advanced KYC Accounts: Withdrawal limit of 200 BTC per 24 hours
4. Institutional KYC Accounts: Withdrawal limit of 400 BTC per 24 hours
Information copied from here: https://www.thecryptobreakdown.com/guides/mexc-withdrawal-fees
There is still no mandatory KYC as of writing otherwise there's likely gonna be an announcement for it.
A snap from my unverified account:
Snap from mexc chatbot under "Registration/Identification":
I'm not sure why your linked article has 5btc limit though, but eh, I'm pretty sure the 30btc is just inflated for marketing anyhow.