Whenever your UAC prompt appears and asks for your permission, you may have noticed that it darkens the screen and temporarily turns off the Aero interface – and it itself appears without transparency. This happens in Windows 11. Windows 10, Windows 8, Windows 7, and Windows Vista too. This is called Secure Desktop.
UAC Prompt disables Aero and dims the screen
When you use Flip 3D, however, you can see it as having the Aero transparency. You can see it below in the first image right in the front.
This is actually a security feature. Using Secure Desktop prevents other applications from manipulating the UAC prompt. When you carry out any task which is in need of UAC permission, for security reasons, when Windows asks for the UAC confirmation, it separates the UAC prompt dialog box from your running desktop process. The UAC dialog box runs under a secure mode desktop so that any malware which may be running under the regular Aero enabled desktop, will just not be able to access the UAC to authorize any action.