My guess would be they are staking UST (stable coin) on Anchor Protocol. The staked funds are lent to traders. Thats how they can promise such high returns since 20% a year is only 0.055% per day. Traders will typically trade positions with a risk to reward ration of 1:1.5 or higher. These fees are negligible at this point for a position that will take a few hours or days to close. This is how you can trade with leverage on exchanges. Risks are protocol exploit or depegging of the staked coin.