There was absolutely zero announcement yesterday that 100% of all deposits in all banks are guaranteed by FDIC. There was a commitment to cover 100% of SVB and Signature Bank deposits under the systemic risk exception. You can take issue with this, or suggest that they will offer protection for 100% of deposits in the future, and that's fine. I'm not going to argue that point, since I don't know what will happen next.
But to say that the FDIC came out and announced 100% protection of all deposits is no more true today than it was when banks were bailed out in the '08 crisis, and there have been many, many examples of depositors losing money since those bailouts happened.