It looks like you were using Certbot - Generally this is an indication that Certbot encountered a lot of failures running. There's some advice on this particular rate limit on our rate limits page:
This hasn't been much of an issue of late because of Automatic recycling of pending authorizations , which usually works, but for some reason must not be in your case.
Once upon a time there was a project - now outdated - that would scan Certbot logs for abandoned pending authzs, called LE_FIND_PENDING_AUTHZ, which is still available on Github but hasn't been updated for ACMEv2. If you're feeling technical, it might be a blueprint for digging up data too.
I'm not really sure what else can help; hopefully someone else has an idea!