Still, there is no official changelog available for cumulative update KB3206309 or Windows 10 insider build 14986.1001. However, Insiders are now reporting that update brings improvements for Windows Defender. The latest update brings new features and a new interface for the Windows Defender.
After installing the update, Windows 10 is now displaying a new message to insiders informing users that Windows Defender is making some improvements.
Windows Defender is making some improvements. We’re working hard on adding new features and finishing our new look, so not everything is ready quite yet. Some features you’re looking for may not be available now, which is why the previous version of Windows Defender is still available on your device.
Also, the new cumulative update brings minor bug fixes and other improvements. If you’re an insider member, you can check your updates for Cumulative Update for Windows 10 Version Next for x64-based Systems (14986). You can also download offline installer for update KB3206309 build 14986.1001 from here.