Hello,
unfortunately the type of authentication the Google Authentication node uses can no longer be verified with Google which is why this warning appears. If you want to access any of the Google Cloud Services such as Google BigQuery or Google Cloud Storage you have to use a Service Account key. Once you have the key you can authenticate using the Google Authentication (API Key) node.
For further details on how to connect to Google BigQuery and how to obtain a Service Account key see the BigQuery section of the database documentation.
Bye
Tobias
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