I think you are only tasked not with the amount you spend on gambling but with the profit you realise from gambling, and it's when you request withdrawal from the casino that they will have to do the math, or you will directly report that yourself to the tax authorities.
If that's how that is being done, then I don't see this as something that will affect any gambler at all, aside from reducing whatever they will win from the casino during cashout.
That's how gambling taxation works, when someone won x amount of money government will take y amount as tax which maybe deducted by the casino itself (most of the fiat casino) or the user has to report while filling his tax but when this is the first time they are going to tax gambling rewards it may look unfair and people always seek how about loss while gambling, why government doesn't allow deduction or exception while you lose, but that's the way it works whether we like it or not.