This was the predictable outcome of shortening certificate length validity to appoint where they are now.

No, because that's not what happened here.

The certificate they failed to renew was issued 2025-Mar-20th, and expired 2026-Mar-20th. That is a 365 day cert.

The maximum length for a new cert is now 200 days, with the 47 day window coming in three years: https://www.digicert.com/blog/tls-certificate-lifetimes-will...

Have you heard of automation? Cron? Certbot? You can schedule cert renewal and it happens automatically. It could be refreshed every 1 day, I don't care. The fact that it's so painful for you means you need to learn a bit more.