How do we know that there won't be any flags on our question? Users won't be notified or made aware of the flags raised.
That's correct; unless you are a ♦ moderator on that site (who have access to the full timeline of a post, including flags) you do not know whether it got no flags and have no way to check it.
There are some ways to know it did get a flag: close votes are stored as flags (though it's not clear yet whether those count). You can see those if you have 250 reputation, and the
'Possible duplicate of' 'Does this answer your question?' auto-comment is visible for everyone. If the requirement turns out to include no flags on the comments and answers as well, you could watch for deleted comments/answers as well. Those are often initiated by flags, either users flagging them or automatic low-quality determination flags raised by the system.
Is it aimed at getting non controversial questions?
We can only guess, but those were exactly my thoughts as well. It's a nice, subtle touch to current events.