One fairly common complain among gamblers is they are allowed to make a deposit at casinos and lose their money without any issue, but if they happen to win and they want to make a withdrawal then they are hit with a KYC request almost immediately, Tonybet a fiat Estonian casino was fined more than 400,000 pounds for this practice and it seems the regulators are now interested in making reforms to the laws and force casinos to also make checks on those gamblers which have lost a lot of money.
Since they are KYC casinos there shouldn't be more threat in demanding for the more statutory recognition in getting the user verified through their system, but it must also be noted not to allow the casino company get this as an advantage over the winner is other to denied them from receiving their winnings, if the case was looked into and definitely found to be a means to sabotage then i think it's also proper to file a suit against the casino for government intercession, even though it's something rare that the casino refused to pay the winner his money by introducing bunch of verification task.