In the given scenario, a rate limiting policy has been applied to the SOAP API and a global error handler is configured to handle HTTP:RETRY_EXHAUSTED errors with a 429 status code. The rate limiting policy will trigger when the client exceeds the allowed quota of API calls. Since the HTTP:RETRY_EXHAUSTED error specifically catches quota exhaustion errors and the error handler is configured to return a 429 status code, the expected HTTP status returned to the client when the quota is exceeded will be 429. This error code indicates that the user has sent too many requests in a given amount of time ("rate limiting").

MuleSoft Documentation on Error Handling

HTTP Status Codes