This option just popped up on my account today. I don't honestly know what it is... it seems you have to qualify for it before they'll tell you why you should try to qualify for it?
But I get an ! on "Ad layout", with no real explanation. Clicking on "Fix This" takes me to a very generic:
To my knowledge, ads aren't too close to the navigation, and they're not in a location that would encourage accidental clicks... I've had the same layout for years and years! My first banner is 300px below the navigation, and a bottom banner is 110px below the "Previous" and "Next" buttons. And I have the interstitial banners turned on, but of course Adsense manages their location.
So how am I supposed to narrow down what the issue is? Or is qualifying for the "User First" program even worth the effort?