Groove Music, Xbox, Alarms and Camera apps on Build 10166 have received updates. Groove Music comes with changelog while Xbox has some menu changes that we could see. Camera and Alarms have seen change in version without any visible changes.
Groove Music changelog:
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Improved default image
Better Narrator integration
New OneGuide menu option
Store icon has changed
Send feedback gone from main menu
Camera and Alarms apps have also received minor updates and you can notice the change in versions below. Though there are no visible changes.