Which Let's Encrypt server URL should a cert-manager test issuer use to avoid production rate limits?

Answer: https://acme-staging-v02.api.letsencrypt.org/directory

Explanation

The staging directory issues certificates from an untrusted test CA, but you can retry as often as you need while you debug an issuer. acme-v02.api.letsencrypt.org is the production server, where repeated failures can hit rate limits. Switch spec.acme.server to production once issuance works.