The casino does not ask KYC at the time of registration is to avoid new users from running to another casino because it is already faced with choices that are not liked because KYC is not something that players like even though this is no longer avoided.
And asking KYC when withdrawal of course there is a reason usually when the casino detects suspicious activities, but the reason is still unpleasant for the players and I have experienced this sometimes, and when asking the reason it was said because it detected suspicious things even though I only did normal, and What is more unpleasant sometimes casinos cannot answer the real reasons from the necessity of KYC to withdraw funds.