Let’s Encrypt’s press release:

https://letsencrypt.org/2025/01/22/ending-expiration-emails/

So, what’s the problem?

I would say: There is no problem. To me, those mails are more annoying than helpful, so I’m totally fine with this.

First of, it’s rather trivial to setup a certificate check to make sure your endpoints have the correct certificates, and send out a mail (or other warning) when expiry is around the corner. This doesn’t only provide a warning when a certain issued certificate expires, but also makes sure that the correct valid certificate is actually being used at the endpoint, which LE’s expiry notification does not do for you.

Secondly, when you let a cert expire on purpose (for example when a certain service is no longer in use, or the SANs of a cert have changed) those expiry mails only add unnecessary work for the people monitoring those mailboxes.

And thirdly I have to agree with them that these notifications result in an obvious non-trivial cost, both in money and in complexity, while providing a free certificate issuance service. Money they can indeed better spend on other, more important parts of their core service.