Apple has brought back the App Switcher!
On watchOS 26 and earlier, you could access the App Switcher by double-clicking the Digital Crown, then turning the Digital Crown to navigate through your recently used apps. You could also swipe left on an app and tap the "X" button to remove it from the App Switcher.
With watchOS 27.2 beta, Apple has changed how you access it. Instead of double-clicking the Digital Crown, you now press and hold the bottom of the screen while inside an app to bring up the App Switcher, as shown in the video.