Assuming that this is truly FDIC insured—I’d say that it seems rather unlikely that the company goes under and you lose your money.
The likely scenario is that this rate is just a marketing stunt and that they drop to around 2% by the end of the year. You’ll get 2.57% for 6 months then they will start dropping the APY.
Ally, Marcus, AmEx and Capital One cut their rates this month to around 2%. This is anticipation for the Fed cutting rates in the coming months.