Why is the first sync of the day longer than other incremental syncs for the Campaign Manager connector?
Connector: Google Campaign Manager
The first sync in a day performs rollback sync for dates within the rollback window, which is hard coded for this connector as 15 days.
According to the Google's Documentation
Campaign Manager 360 continues to add data within 7 days to ensure that data is included in reports as accurately as possible. As a result, we request a report for the last 15 days during each first sync in a day. The next syncs request a report only for the current day.