When I do a full account export, why is the size of the exported backup archive larger than the size of the backup archive shown in the application?

There could be a discrepancy in the size of the exported backup archive because the backup archive shown in the application displays only the files owned by the user. It does not include the files shared with the user.

When you export a user’s archive, the exported data will include both the files owned by the user and the files shared with this user. Hence, when you export the user's Google Drive (or OneDrive) data, the size of the export backup archive will be larger than the size shown in the application.

Note: This discrepancy in backup archive size will occur only if you had chosen to back up all the Drive documents in the backup settings.