Samsung's One UI 9, June 7 -- The button is gone. But the protection it offered is no longer optional.

the moment a user opens the power menu on a running device, the phone enters Lockdown Mode on its own, regardless of whether the screen was already unlocked.

That might sound like a minor software housekeeping decision. It is not. It addresses a gap in Galaxy device security that has existed, largely unacknowledged, through multiple generations of One UI.

Under previous versions of One UI, Lockdown Mode had to be triggered deliberately. A user had to recognize the threat, open the power menu, locate the Lockdown button among the power-off and restart options, and tap it. In the roughly five seconds that process takes, a thief who has ...