@_az What version of Certbot were you using? Was there anything special about the repro? Our own internal blackbox monitoring using Certbot to issue for wildcard names (with a random domain component to avoid authz reuse) against staging didn't catch this but I was able to repro using Lego.
You probably caught the status page chatter but we've identified the problem and fixed it. Based on my own repro experience I suspect accounts that created buggy orders during the outage period will continue to see some 500's if they submit new order requests for matching names with the same ACME account. I recommend rotating the staging ACME account or waiting 7d for the pending orders to expire.
Apologies for the disruption. We'll be digging deeper into the root cause over the next few days.