Hey, actually it's not Samsung related. Sometimes, my Facebook app is unable to exit by the Back button. But once u kill the app (meaning go to Recents and close app from there), relaunch Facebook app again and try with Back button to close, it works now. Seems like Facebook glitch.
Some apps like YouTrip doesn't allow closing by Back button, the most initial page it will land is the Dashboard screen, then u have to kill the app manually.
Sometimes, Shopee also has this glitch, after completing a product review, then the Back button cannot close the app as well.
