Cannot Read Bigquery table sourced from Google Sheet (Oath / Scope Error)

You are authenticating as yourself, which is generally fine for BQ if you have the correct permissions. Using tables linked to Google Sheets often requires a service account. Create one (or have your BI/IT team create one), and then you will have to share the underlying Google Sheet with the service account. Finally, you will need to modify your python script to use the service account credentials and not your own.

The quick way around this is to use the BQ interface, select * from the Sheets-linked table, and save the results to a new table, and query that new table directly in your python script. This works well if this is a one-time upload/analysis. If the data in the sheets will be changing consistently and you will need to routinely query the data, this is not a long-term solution.

I solved problem by adding scope object to client.

from google.cloud import bigquery
import google.auth

credentials, project = google.auth.default(scopes=[
    'https://www.googleapis.com/auth/drive',
    'https://www.googleapis.com/auth/bigquery',
])
CLIENT = bigquery.Client(project='project', credentials=credentials)

https://cloud.google.com/bigquery/external-data-drive