Hi all!
There is already a rate limiting mechanism in place to protect customers instances, to keep then usable. The mechanism is used for all endpoints including REST APIs. Our Jira SREs try to tune them to not harm our customers. There might be some situations when SREs need to change standard thresholds which results with visible or increased number of 429 responses.
We are still working on finding the best mechanism/thresholds so we are not able to provide any rules which would be valid for a longer period of time.
In cases of seeing 429 responses I would recommend postponing and replying requests at lower rate if possible.