The next big feature update for the Xbox One, version 1910, is rolling out soon. Naturally, that means that it's time to start testing out the next one. Those on the Skip Ahead ring are already testing out version 2004, which is a major release that's known as 20H1 or Vibranium on the Windows 10 side of things.
But Xbox works a little differently than Windows 10 does, since Xbox gets monthly feature updates. They tend to be a bit more minor than the big ones that come twice a year, and they often include features that didn't quite make the cut for the major release. That next minor release will be version 1911, as Preview Alpha ring testers will start to see today with a new build.
The build itself is build 18363.8038, and it doesn't contain any new features. Right now, it's all about "setting up the new framework for what is coming." This isn't unusual, as there are always a few builds without anything new, and then Microsoft makes an announcement about what's coming in the feature update.
As the version number indicates, this update should be available in November.