I think a lot of people (IMO, >90%) are depositing via fiat (INR) on Stake.com from India. Stake.com is trying both the carrot and the stick to change that situation (although with the convenience of UPI, I don’t see it changing anytime soon). On the one hand, Stake.com is charging a hefty fee for fiat cashouts (almost 15%), and on the other hand, rewarding those who are making crypto deposits.
I also received a small carrot yesterday in my email

This bonus was sent on the same day to another user but with a different title, for users from India it is as you said whereas for me it is a July subscription bonus and for other users with different titles like ''Esports bonus'' well basically bonuses are sent randomly to eligible users. Have you confirmed that all users who deposit using INR get this bonus and is the bonus around $15? (or based on VIP level). By the way I'm curious it seems that users from India are a bit prioritized, I suspect India is the largest Stake.com user in the world and I wouldn't be surprised if that true.