By default macOS allows you to open apps from the official Mac App Store only. If you have this still set as your default you will be seeing the warning when you try to open an app for the first time.

Apple's macOS Sonoma gives you the ability to turn any website into an "app" you can dock and open like any other. Here's how to do it, and what the benefits are.

How to find all open windows for an app using the App Switcher While the Shelf feature is great, it’s not intuitive—and you only get to see little previews of the windows for a couple of seconds.