Welcome @Hawk777
I can't explain all the twists and turns but it is most likely related to a Let's Encrypt incident that required revoking some of their intermediates. Why that only caused problems for you in recent days I can't explain. Maybe it took that long for google's mail servers to recognize or honor the revocations? See the incident here: 2026.05.08 Gen Y Cross-Certified Subordinate CAs missing serverAuth EKU
During that incident LE triggered ARI renewals so capable systems would renew their certs immediately. Sadly, your Certbot v4.0 does not support ARI. You would need at least v4.1 for that. See: certbot/certbot/CHANGELOG.md at main · certbot/certbot · GitHub I'm guessing that v4.0 came from your pkg manager. You may want to consider using the snap or pip install instead. See: https://certbot.eff.org
That has no bearing on this or what you've seen. LE uses YE1 or YE2 at random for various reasons.