What is a pin-shaped icon on the Recent Apps screen?
When you clear apps in the Recent Apps list, pinned apps won’t be removed. Tab the pin-shaped
icon to keep apps in the Recent Apps list.
How to use
1. When an app is pinned, it will not be removed with Clear All, swiping, or the X button.
2. Dual window, Pin, and Close buttons may appear slower when you open Recent Apps.
Please be assured that it is a sign of normal operation due to Android OS.
3. Use Clear All to remove apps (except pinned ones) to make free space.