Let’s Encrypt will be reducing the validity period of the certificates we issue. We currently issue certificates valid for 90 days, which will be cut in half to 45 days by 2028.
This change is being made along with the rest of the industry, as required by the CA/Browser Forum Baseline Requirements, which set the technical requirements that we must follow. All publicly-trusted Certificate Authorities like Let’s Encrypt will be making similar changes. Reducing how long certificates are valid for helps improve the security of the internet, by limiting the scope of compromise, and making certificate revocation technologies more efficient.
Unfortunately some apps require the certificate be bound to the internal application, and need to be done so through cli or other methods not easily automated. We could front load over reverse proxy but we would still need to take the proxy cert and bind to the internal service for communication to work properly. Thankfully that’s for my other team to figure out as I already have a migration plan for systems I manage.
Why can’t you just have a long lived internally signed cert on your archaic apps and LE at the edge on a modern proxy? It’s easy enough to have the proxy trust the internal cert and connect to your backend service that shouldn’t know the difference if there’s a proxy or not.
Or is your problem client side?