It is not a free gift, but a temporarily interest-free loan.
This is what really happens:
You are borrowing up to 50 US dollars from Binance under the cross margin feature.
For a single day, no interest is charged (this is the "coupon" feature).
After the one-day bonus period ends, interest begins to accumulate at the normal rate unless you repay the loan.
You must have sufficient collateral to borrow.
So consider the coupon as a short-term interest-free loan, and not as free money or a gift. If you do not repay it during that day, you will start paying interest like any normal margin loan.$USDC #préstamos