it's not the FDIC per se, it's the fed that bought the bonds (mostly mbs's) at face value so that the bank wouldn't have to sell them at market at a significant discount to get cash to cover withdrawals. for what it's worth, apparently the IMF is the final entity backstopping this not-FDIC-not-a-bailout operation. the net result is the same in regards to how it affects risk/reward for banking operations.

https://nitter.lacontrevoie.fr/TyrantsMuse/status/1635083490256617474#m