iOS release notes reveal that Google is making a couple changes to its Home app. Once updated, the Feed tab will show important activity from supported devices, like your Nest Cam. Last year, Google said users would be able to watch full video clips or listen to audio clips in the Feed tab, and this update could enable that.
The release notes also indicate that the app will make it easier to turn lights on and off with the Lights quick action. It's still unclear what's changing, though. As 9to5Google notes, those shortcuts are already available at the top of the main tab.
There's a chance that Google is making these changes in preparation for the new Nest Aware, which is scheduled to launch in early 2020. That will bring "event-based recording" to Nest cameras, so showing those clips in the Feed makes sense.
The update, Google Home 2.19, is available on iOS, and it's beginning to roll out on Android. The changes will be made as a server-side update over the next two weeks.