Thanks for the link, but while I am searching now even on bitcointalk there are many members said Kucoin ask for KYC compliance even if their limit is below the level what they mentioned for non verified customers and also some account under froze until they complete KYC so with any centralized exchange regarding KYC or no KYCed account the user should be asked to verify their Identity at anytime which is also mentioned in their ToS so yes there is no guarantee that someone can withdraw as non verified user forever.
Requiring KYC is possible under certain conditions since it is really a centralized exchange like suspicious activity detected. I'm a regular user of kucoin and fortunately, i never experienced requiring KYC yet.
While other exchanges have accounts limit, 50k limit for level 1 is really huge. But nah, i found lots of complains about polo, shattered reputation in those years that i decided to ignore them and only use kucoin even though it has lower withdrawal limits.