Win11 Windows Security icon in the system tray disappears after a system update

Because Windows Security still opens and toggling its taskbar setting restores the icon, the missing icon does not necessarily mean protection is disabled. Open Windows Security and confirm that Virus & threat protection, Firewall, and Device security show their current status. Then open Task Manager, select Startup apps, and ensure Windows Security notification icon is enabled. In Settings, open Personalization, Taskbar, expand the system-tray options, and enable the icon. Install pending Windows updates and restart. If the preference resets again, note the update number and test after a clean boot; taskbar utilities or startup-management software may be rewriting it. Run DISM followed by SFC from an elevated terminal to check component files, but avoid registry cleaners or Defender-disable scripts. If protection remains healthy and only visibility resets, submit the Windows build, update number, and reproduction steps through Feedback Hub as a taskbar persistence issue.