Which version were you on before the upgrade?
I agree with Sandeep’s comment to recheck the current implemented REST API calls in the code to see if any have become deprecated. Around this time, there were many changes to the API connectivity and feature enhancements for Azure. IdentityIQ 8.4p2 is now available!
You’re experiencing azure rate limiting due to some reason related to the above. Maybe there is an obsolete endpoint being called that automatically retries. Or too many simultaneous workflows, bulk operations are processed without batching or retry logic is aggressive/misconfigured.