It is indeed Cloudflare, very strange.
Resolved, probably?
Okay, is DigiCert having problems today? That's CloudFlare's primary provider, so the LE certificate might be a stop-gap applied by CF.
If Cloudflare gets right to the wire and then is like "Oh, DigiCert couldn't issue for whatever reason" then that's a process problem at Cloudflare not DigiCert.
A reasonable strategy is to renew say, 30 calendar days in advance. But that would mean Cloudflare (or at least, some automated system that nobody was looking at) knew 30 days ago this would happen and nothing was done about it.