Lockdown mode was introduced in 2018’s Android 9 Pie release as an optional feature users could add to their power menu. When enabled, lockdown mode hides notifications and disables all forms of authentication except for the user’s primary authentication (PIN, password, or pattern). In Android 12, Google made the lockdown mode toggle appear by default in the Android power menu, though some OEMs hide it or offer their own, similar version of the feature elsewhere.
Android 15 will further restrict USB access in this mode to help defend against attacks.