Bakup log rotation
Plesk does not rotate backup logs and we needs to delete them by manual.
Backup log might be very big, therefore Plesk should rotate backup logs automatically to prevent oppression of disc capacity by increasing backup logs.
Related KB: http://kb.odin.com/en/113748/
Thank you for your input!
Unfortunately, we have to close your request, because over the years it has not become quite popular for further implementation.