With build number 47.1.A.2.374, the update comes as a security Android fix for the month of October. Apart from this, there is no other information about this update and the changes it is going to make.
It might take some time to show up on your XZ1 and XZ1 Compact so all you need to do is wait.
Let us know your views on the changes it brings. Keep following The Mr. Phone for all technology related updates!