Is this clock screen lock, screen saver, or anything else?

I am using RHEL 8.5. After the system is idle for a while, the screen will be all black. Then, if I click the mouse, there will be a clock, as shown in the screenshot attached. I had thought it is screen lock, so I searched google and turned it off in Settings-> Privacy->Screen Lock. But the clock still shows. I had thought this is a screen saver, but I cannot find its settings in Settings to turn it off. So, what is this clock, and how can I turn it off so that the desktop is always shown?