Hi there
I have been playing some time now on justbit.io. Won some money, and my account stands approx 8 mbtc. I asked to withdraw 5 mbtc and today they asked me for KYC procedure (ID and other stuff). By their site states explicitly that they do not ask for KYC if crypto was used to deposit. This sounds me like scam. They will not pay me
Any centralized and regulated service platform may ask for KYC at any time even though there isn't mandatory KYC policy but with the site you mentioned they clearly stated that before withdrawal of funds the user needs to pass KYC so its you negligence towards their terms which costs you 8mbtc but you can withdraw the funds once you complete the KYC and whatever they ask so this isn't a sign of scam but make sure you didn't fall for fake website.