Microsoft has announced that it is testing a new 4K dashboard for the Xbox Series X. With the new update, Xbox Insiders in the Alpha and Alpha Skip-Ahead rings will have access to the increased resolution of the UI.
The new update will see changes such as the Home, Guide, and other areas of the UI to be displayed in a higher native resolution. Xbox has previously been running dashboard UI elements at 1080p.
While the update is rolling out to the Xbox Series X, Microsoft didn't mention anything about Xbox Series S so we'll just have to wait for the news from Microsoft.