In the top description we can read:
"Version 2211 will introduce a temporary option to hide the new experience and return to the classic Outlook navigation bar. If you choose to opt out and see the prompt for feedback, please take a few moments to submit your reasons. Outlook may also invite you to re-evaluate the new experience when new apps or more app-related functionality is introduced in the future"
a temporary option to hide the new experience = we don't like this "new experience" and we want a PERMANENT option to hide it
If you choose to opt out and see the prompt for feedback, please take a few moments to submit your reasons = folks then give this feedback 🙂
The fact is that we all don't want apps in Outlook, we use the taskbar for this. Give the SWITCH permanently and not temporarily.
For all people who didn't know that this was coming. There was a "Coming Soon" button on the top right, everyone could "test" this great new feature.
That's how I noticed it. So for later updates check this corner 🙂