Do you get a more detailed response along with the HTTP 429? I’d be curious about what it says.
Looking at the crt.sh results for your domain, it doesn’t appear that you ran into the actual rate limits for Let’s Encrypt yet. However, even if that were the issue, it would be limited to one environment and should not affect staging. You should be able to verify if this is a rate-limiting error by looking at the full output rather than just the HTTP status code - this would also include which of the various rate limits you’re running into.
It might be possible that Akamai, the CDN that sits in front of Let’s Encrypt’s servers, has some additional request throttling logic that also uses HTTP 429, for traffic that looks like a DDoS attempt or something like that. Both staging and production are behind Akamai, so this logic could have banned you from both endpoints. If you’re not seeing a detailed error message in the response (with something like “urn:acme:error:rateLimited”), that’s likely what’s happening here. That being said, I’m just speculating here, I haven’t seen this happen before.