If I visit a news site with a "share on facebook" widget which uses a facebook endpoint to get my facebook identity, am I an active facebook user?
If I have the mobile app installed which runs in the background getting notifications I never read, am I an active facebook user?
"We define a monthly active user as a registered Facebook user who logged in and visited Facebook through our website or a mobile device, or used our Messenger app (and is also a registered Facebook user), in the last 30 days as of the date of measurement."
'The social network said in an email to SocialTimes that it “wanted to provide a cleaner metric,” so starting with its third-quarter-2015 earnings report, it no longer counts what it called “third-party pings,” or people who did not access Facebook itself, but shared content or activity via Facebook Login-integrated websites or applications.'
That's exactly what is under discussion: whether FB conservatively excludes 3rd-party widgets and such when counting activity. They started being more conservative late last year.