The first preview of the recent update to the Windows 10 21H1 feature, codenamed Iron, was released under the first preview version of Build 20133.1000, compiled on May 19 and is part of the rs_onecore_dep development branch. The first preview of the 21H1 is expected to arrive on the Fast channel for the Windows Insider project in late June.
As in the past, this version of Windows 10 21H1 should have no user-facing features, and the new features will be pushed forward in subsequent updates. It’s not clear what improvements 21H1 will bring, but Panos Panay said the feature update will lead to improvements in the start menu.
Microsoft has previously said that new windows 10 features will not follow feature updates, but will be more flexible to release based on the testing of new features. In other words, the new features currently being tested in the Insider channel do not necessarily appear in the next Windows 10 feature update.