[Bug] Unexpected unsupported content type errors

I got reports that this started happening today:

{
  "error": {
    "message": "Unsupported content type: 'application/json; charset=utf-8'. This API method only accepts 'application/json' requests, but you specified the header 'Content-Type: application/json; charset=utf-8'. Please try again with a supported content type.",
    "type": "invalid_request_error",
    "param": null,
    "code": "unsupported_content_type"
  }
}

Adding Charset to the content-type should be acceptable. Didn't see any changes go into the schema so likely an issue internally in the API implementation.

No repository file or test is identified. Start by reviewing the OpenAPI definition and the linked report for the affected request content type; done means determining whether the specification needs a change or whether the behavior belongs to the API implementation.