DeprecationReportBody.anticipatedRemoval

The anticipatedRemoval read-only property of the DeprecationReportBody interface returns the date that the browser version which removes the feature will ship. This value can be used to prioritize warnings. If this property returns null because the date is unknown, then the deprecation should be considered low priority.

let options = {
  types: ['deprecation'],
  buffered: true
}

let observer = new ReportingObserver((reports, observer) => {
  let firstReport = reports[0];
  console.log(firstReport.type); // deprecation
  console.log(firstReport.body.anticipatedRemoval);
}, options);