That has been there since day one of tvOS. It is extremely helpful for navigating open apps, and closing problematic ones.
If you used an IR remote in the past, you may have never noticed this because the IR remote learning feature did not have an option (for some idiotic reason) for the "Home" or "TV" button for the IR remotes until recently.
If you have only used the Siri Remote, I am surprised you have never seen this before, even by accident.