Or that someone asked to renewed it, one of their four bosses didn't sign off the apropriate form, the only person to take that form to whoever does the certs is on a vacation, person issuing certs needs all four of his bosses to sign it off, and one of those bosses has been DOGE-ed and not yet replaced.

expired letsencrypt cert on a raspberrypi at home smells of not paying attention... with governments, there are many, many points of failure.