They're using LetsEncrypt, which is a really common free SSL certificate provider supported by all major browsers and totally automated. The problem is that LetsEncrypt was one of the first CAs (certificate authority) to cut their certificate lifespans down to 90 days. Unfortunately, it appears this hasn't happened since April. My guess, their automation broke or they're just not doing the replacement. Brave and a few other browsers will allow you to click thru the expired certificate warnings, but I believe Safari, Chrome, etc will just NOT without some settings tweaks.
Edited to add: and if you look at the time stamps on the cert issue date, they're from 4:40AM Central time. That says to me some poor ops guy doing it in the middle of the night, not automation.
(Cybersecurity inside baseball: All the browser makers were planning on cutting from 2 year to 1 year to 180 days to 90 days down eventually to one day lifespan to force sites to automate their renewals, for safety. It wouldn't matter if a private key was compromised with more key rotation. This also ties in with a broader move to ephemeral ciphers and perfect forward secrecy, it's all about making sure certain intelligence agencies everyone thinks are totally off the leash from reading all our internet traffic. Lots of interesting speculation around quantum computing as well.)