Windows may be one of the most popular desktop platforms, but not every part of the OS sees as much popularity or use. A case in point is the Timeline feature on Windows 10 that was added in the April 2018 update to the OS. The feature aims to show you current and past activities across a time period on devices connected to the same Microsoft account, and is accessed through Windows + Tab key combination. Microsoft is now killing the cross-device syncing function on the Timeline feature with the latest Windows 10 Insider Preview Build.

With the latest Windows 10 Insider Preview Build 21359, Timeline will no longer upload new activity to the associated Microsoft account (via Thurrot).

If you have your activity history synced across your devices through your Microsoft account (MSA), you will no longer have the option to upload new activity in Timeline. AAD-connected accounts won’t be impacted. To view web history, Edge and other browsers have the option to look back at recent web activities. You can also view recently used files using OneDrive and Office. Note: Timeline and all your local activity history still remain on Windows 10.

Timeline and all local activity history will remain on Windows 10, it's just that you will no longer be able to use the advertised "pick up where you left off" functionality with Timeline. This cross-device history and activity syncing was one of the highlighting features of Timeline, spanning across Windows 10 computers and Android devices using the Microsoft Launcher. But Timeline was removed from the Microsoft Launcher in 2020, and now this particular change makes it a shell of the intended vision behind the feature.

Considering the fact that most people do not even recall that such a function used to exist, it wouldn't come as a surprise if Microsoft does end up axing Timeline as a whole. For now, if you do use the feature, you will have to contend with the fact that cross-device syncing will go away when the update hits the stable channel.