Back in February 2021, Google had sunset the Lineitems endpoint in the DoubleClick Bid Manager API, which we had been using to get data for the authentication and account selection process. We have since replaced that with the recommended DV360 API, but kept a reference to the older API as a fallback.
We discovered when going to remove the fallback, that there are still users with older authentication tokens that were using the fallback of the older API. So we need to ensure all users have updated their authentications for Google Display & Video 360 so their queries do not break when we remove the now deprecated API references.
We have scheduled the removal of the old API fallback on May 6th, 2021. On or before this date, please go through the re-authentication process for the Google Display & Video 360 data source to avoid disruptions and errors.