What changed
Updater-enabled builds show a colored indicator when a newer stable version is available for the current OS and CPU. Automatic checks start on by default; an existing off setting is preserved. Downloads and installation remain separate user actions.
What to do
Preview 4 and earlier require a manual first update. Preview 5 includes the interface on macOS, Windows and Ubuntu. The stable update feed currently offers no update; a merged fix alone does not trigger the indicator.