Call of duty

I have at&t internet with a 215gb limit a month. It costs $10 for an extra 50gb after I go over that. We recently switched our cell phones to an at&t unlimited plan from verizon. Since we've changed I haven't been able to play call of duty mobile using data instead of wifi. What's happening here? Am I going to have to pay extra on our internet bill every month just to play a game? I tested both of them and the mobile data test had way higher numbers than the wifi. Why can't I play this game using data instead of wifi? I've tried to play multiple places and it never works using data. (Edited per community guidelines)?