This is the error we’re getting, you may be able to see this with fly certs show <hostname>:
Error authorizing certificate "<hostname>": Error creating new order :: too many certificates (5) already issued for this exact set of domains in the last 168 hours: <hostname>, retry after 2023-03-06T09:51:27Z: see https://letsencrypt.org/docs/duplicate-certificate-limit/
This happens when you add/remove a domain several times, or get certs for it from other services.