Dynamic translator not working as expected when called from a businessrule

[Prem5]

Hi all,

We have a business rule calling the Google translator api to translate a field value from different languages to English. Below is the code

var gr = GlideRecord("asmt_metric_result");
gr.addEncodedQuery('metric.metric_type.evaluation_method=survey^sys_id=afc4d440db8e715023d73423e29619d5');
gr.query();
while (gr.next()) {
    var sobj = sn_dt_api.DynamicTranslation.getTranslation(gr.string_value.toString(), {
        "targetLanguages": ["en"],
        "additionalParameters": [{
            "parameterName": "texttype",
            "parameterValue": "plain"
        }],
        "translator": "Google"
    });
    var trans = sobj.translations[0].translatedText.toString();
    gs.info("Translated text: " + trans);

    gr.u_string_value_english = trans;
    gr.setWorkflow(false);
    gr.autoSysFields(false);
    gr.update();
}

It was working fine for the past 1 year and started returning an error as below from the past one week

sn_google_trans: Error while translating the text to language using Google Cloud Translator. Error:Request had insufficient authentication scopes.Response received:{
  "error": {
    "code": 403,
    "message": "Request had insufficient authentication scopes.",
    "status": "PERMISSION_DENIED",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.ErrorInfo",
        "reason": "ACCESS_TOKEN_SCOPE_INSUFFICIENT",
        "domain": "googleapis.com",
        "metadata": {
          "service": "translate.googleapis.com",
          "method": "google.cloud.translation.v3.TranslationService.TranslateText"
        }
      }
    ]
  }
}

I thought it is an issue with the Oauth credential setup, but we are getting the tokens as usual. Any inputs on how to trouble shoot this issue is appreciated.

PS: Yes, we the Dynamic translation spoke properly installed and configured.