'Could not load credentials from any providers' error

This looks like its caused by EC2's Instance Metadata Service (IMDS) throttling.

We throttle queries to the IMDS on a per-instance basis, and we place limits on the number of simultaneous connections from an instance to the IMDS.

If you're using the IMDS to retrieve AWS security credentials, avoid querying for credentials during every transaction or concurrently from a high number of threads or processes, as this might lead to throttling. Instead, we recommend that you cache the credentials until they start approaching their expiry time.

While caching would be a good workaround, I much prefer to re-use my service clients, avoid creating them for every API call as it leads to higher latencies and unexpected issues such as IMDS throttling and increased KMS calls (if you use KMS CMK).

Ref