The firmware update is dated the 13th February and brings the following changes:
Both the Surface Book and Surface Book 2 have received an updated DTX component, which manages the docking and disconnection of the base unit. The update fixes a bug related to the bright colour scheme in Windows 10 which could have led to display problems.
The Surface Book 2, in particular, has received an update to the Marvell driver taking it to version 15.68.17017.115, which brings general improvements in the stability and performance of Bluetooth and WiFi connections.
Surface Book owners can download the update by Checking for Updates in Settings.