Monumental Cock-Ups

Let's Encrypt is an excellent service and idea, and well executed.

Unfortunately, they had a bug in their processes that results in a number of possibly bad certificates.

Thee short answer is that if you have a site or service that relies on LE via certbot or ACME, you need to go ahead and manually force an update. My cert has been updated within the last two days so it may have a valid cert from after the glitch was discovered and fixed, we'll see.