When CubeBackup creates a backup snapshot, does it backup all data each time, or only the changes?

Incremental algorithm

CubeBackup employs an incremental backup algorithm, so that only new or modified data is backed up each time.

Microsoft 365 backup snapshot

CubeBackup behaves much like Git or Mac OS Time Machine, keeping all historical versions of your data in snapshots. Actually, CubeBackup employs a SQLite database to track changes, so that it understands the full version history of all SharePoint and OneDrive files, Outlook Mail, People and Calendar data in your Microsoft 365.

Mail snapshot