You know how casinos have set certain slots to only pay a certain amount to a winner, it it also possible that casinos are using an algorithm to limit how much it can payout for players coming from certain locations to avoid being dragged into legal disputes if a player is paid big money and the local authorities want to know the source and the alike?
I think this is very unlikely to happen.
And if there is any law that limits winnings, the casino needs to make players well informed about this and also limit the bets before this happens.
Limiting the bet is something very simple to do, because always before the bet, the system knows how much you are betting and what the multiplier is, so they know how much you can win if you hit. It would then suffice to limit the multiplier factor.
Any other way of limiting without the player knowing would be viewed with a lot of scorn by the community.