Welcome @WisTex
The limit on too many pending authorizations (link here) is usually an ACME Client that is faulty.
Were there any other setup changes to AutoSSL recently? Because it reminds me of someone using AutoSSL hitting this same limit recently.
See the below thread for that situation. Try resetting the account unless your account has been used to get a rate limit exemption or is on the allow-list for ECDSA certs. You would know if yours had these.
I've linked to the bottom post which gets to the remedy but perhaps earlier posts in that thread would be helpful too. It's possible something else has gone wrong with AutoSSL but this seems good place to start.