> At the same time, they’ve essentially raised the insurance limit to infinity.

No, they haven’t. The systemic risk exception was used during the last financial crisis for some banks and not others, so using it now doesn’t raise the insurance limit, actually or “essentially”. There is (still) no guarantee that it will be used for any particular failure in the future, just like there wasn’t after the last financial crisis, and people have lost funds in excess of the $250K insurance limit since the last use of the systemic risk exception.