Here's the good news:

This is where decentralization truly shines. Even with current pool centralization concerns.

Scenario: Foundry (the currently biggest pool at ~ 32%) goes down for a day across the board. (This fwiw would be about 100x as incompetent as the ECB as there's Foundry's money and reputation at stake, the ECB is a monopoly.)

The block time will expand with a few minutes and the backlog may grow.

However, most mining operations also don't like losing revenue, so assuming that Foundry would immediately shut down their stratum servers upon not being able to actually produce blocks, miners will switch to another pool either instantly (configured fallback pool) or within the hour (manually) and block spacing will no longer be affected.

In any case, the deviation will be short lived and totally within normal block spacing distribution: no transactor will likely even notice, except when looking at pool stats because a discrepancy would show: "Foundry did not produce any blocks that day, wth?" and of course the endless FUD on the bird app / half of IBIT being sold because the Investoors Sans Technology shall shit their pants.