In some case, e.g. when BigQuery tables are recreated, the subscriptions need to be cleared.
This can be done by rewinding subscriptions to a future date (make sure to change 2020-08-21 to some future date):
PROJECT=<your_project>
for entity in blocks actions logs transaction_logs
do
gcloud alpha pubsub subscriptions seek \
projects/$PROJECT/subscriptions/mainnet.dataflow.bigquery.${entity} --time=2020-08-21T23:00:00.000Z
done