After updating Backup client from Acronis v9.x to ABR10, incremental backups are consistently much larger than before the update.
The exact cause is unknown. It does not affected all ABR10 clients and seems to mostly affect MS Exchange servers.
The issue is resolved in ABR11. This is not yet available for Kaseya Backup customers, but will be integrated in the next release of Kaseya Backup. At this time, the only solution is to uninstall ABR10 and install Acronis 9.x. Please contact Kaseya support for instructions and a license key (Kaseya Backup 4.0 does not support automated installation of Acronis 9.x).
Kaseya Backup 4.0
Acronis Backup and Recovery (ABR) 10