I do get that in withdrawing funds on KuCoin, it doesnt really need KYC verification but the thing is, as you reached for the support yourself you may as well get the things done since they know what they are doing exactly. If its KYC documents they needed then provide it or else it may look that it is involve in some fraudulent activities. If they detected that then that is the valid and only reason why they want you to submit KYC. Especially if it involves a huge amount of money having problems. Even in banks and other institutions, they are looking for verifications just like this one.