"The wagering requirements are put in place so that you don't use our platform as a money laundering service" is what they always say.
It's not a false one. Imagine there's no wagering requirement on deposit. You will be able to use them to break the blockchain link, as they say you can use the casino as mixer. Well, 1x wagering isn't really something big when you play for a little time. It's too easy to chase, though OP's casino has a weird 5x requirement.
Money laundering is a serious problem and it is valid enough for regulators to ask these casinos to comply and make wagering requirements on deposits before allowing them to withdraw. But a 5x wagering requirement is crazy. Most betting sites I encountered only ask me to wager once.
But maybe OP wagered once using very low odds like 1.05. I wonder if very low odds are enough for casinos to allow withdrawals. They might want you to bet 20x with an average odds of 1.05 in order for withdrawals to be allowed.