I have no idea whether or not Facebook is restricting my news feed but I know 100% for a fact that my desktop and mobile are completely different. On mobile, I never see activity from some friends while on desktop it is the complete opposite.
No, Facebook is not restricting the content you see on your News Feed to just 25 or 26 friends. Over the last few months, a hoax has been making the rounds on the social network. It claims, in essence, that Facebook has implemented an algorithm change that means you will only see posts from a select few of your friends. Anyone else is flat out of luck.
