I think there are several CEX exchanges out there that never show any seriousness especially the promised rewards for participants after the end of the promotions. Sometimes, I see these promotions on some of these exchanges as a way to increase their profits through trading activities but never distribute the rewards because it is their gimmick to make users believe that these exchanges are doing well, unfortunately, they are not.
I have participated on a new project coin listed trading competition on certain exchanges but never received the rewards, and so are some of the CEX exchange's think they can make gains through deceptions. To participate on promotion on CEX exchanges, these few exchanges maybe reliable in terms rewards distributions, Binance, Kucoin, gate etc.