[tomxor]

Not sure. Unless this is sustained for a long time it shouldn't affect autorenewals which are done well in advance of expiry. So it _shouldn't_ affect cert expiry unless people are still manually renewing and leaving it to last minute.

[edit] Unless the attackers identified a bug in certbot (commonly used autorenewal scripts), e.g what happens when LE is unavailable when autorenew is triggered - you'd hope it would retry periodically until LE is restored, but perhaps not. If not you could time the DDoS just right to ensure a specific cert does not get renewed even after the DDoS stops, then maybe a couple weeks later it would expire... But that's relying on such a bug existing and the site owners not noticing it (LE will also email the registered email address eventually regardless of autorenewal scripts), so maybe this is too much of a stretch.