Looks like they want to compete with Uniswap, Binance and OKEX and steal some UNI volume 
by offering this $50 credits, It's not bad, it's a great offer but I guess most of the people already sold their UNI. These big exchanges can make a lot of money by trading fees that is why they create an alluring promotions/marketing.
by offering this $50 credits, It's not bad, it's a great offer but I guess most of the people already sold their UNI. These big exchanges can make a lot of money by trading fees that is why they create an alluring promotions/marketing.