_transfer_status artifact in the destination schema after each successful transfer. It contains one row per model with the timestamp of the last successful sync.
Schema
BigQuery
For BigQuery destinations,_transfer_status is a view rather than a physical table. It is backed by BigQuery’s __TABLES__ metadata and a _transfer_status_cache table, which caches timestamps to prevent schema evolution operations from inflating the last-modified time.
The _transfer_status_cache table is also present in the destination schema and is used internally by the view; it does not need to be queried directly.