birthdate searching not working for Patient

https://test.com/api/ImagingStudy?_include=ImagingStudy:subject&_include=ImagingStudy:referrer&_total=accurate&_sort=-_lastUpdated&_elements=id,identifier,subject,name,gender,birthDate,modality,description,status,started,numberOfInstances,reasonReference,referrer,extension,location,resultsInterpreter&_count=10&subject:Patient.birthdate=1969-09-14

I have published latest 4.0.728 release version fhir api.
Tried to perform above operation but birthDatesearch not working it is giving below error

Earlier it is working now giving below error

{
"resourceType": "OperationOutcome",
"id": "eabf175d-e2e7-4523-bc6b-aead26133319",
"meta": {
"lastUpdated": "2026-05-01T14:14:59.6079153+00:00"
},
"issue": [
{
"severity": "error",
"code": "throttled",
"diagnostics": "The request rate has exceeded the maximum API request rate and is being throttled. Please try again later."
}
]
}

{
"resourceType": "OperationOutcome",
"id": "79efdb6a-ac6d-4c16-a4bb-8b99eab19ddb",
"meta": {
"lastUpdated": "2026-05-02T07:24:41.8957183+00:00"
},
"issue": [
{
"severity": "error",
"code": "too-costly",
"diagnostics": "The operation was stopped due to the underlying request being too resource intensive. If possible, try narrowing or changing the criteria."
}
]
}

Start by reproducing the supplied ImagingStudy API request against the published 4.0.728 FHIR API, including the subject:Patient.birthdate criterion. Review the returned OperationOutcome responses and the eight-comment issue thread for expected behavior and reproduction conditions. Done means the birthdate search behavior and the throttled or too-costly outcome are understood and a concrete corrective scope is identified.

Written by the indexing model from the issue text.