Now that you've mentioned this, this could happen especially when big money is involved, things can flow a different way.
If the AI's developer just want enough recognition and enough money in exchange for the gambling AI built, then there will be no problem regarding bribery of tweaking the predicted results to the benefit of the casino site. However, if the developer wants to tie up with the giants or whichever casino that will give them the amount they need or want, then there's a possibility that there will be an agreement between the two for the mutual benefits, hence, producing a tweaked version of results being in favor to the house for more profits.
It's also possible to counter AI with an AI. It will just be a matter of detection and of course, maintenance of the system to know which works better than the other. To relate, but not entirely about gambling, this is in connection with AI vs AI, there's now a feature of turnitin wherein it is able to pinpoint which phrases or paragraphs are written by chagpt. This could also happen in the future in gambling AIs to determine and counter another AI.