"If you’re seeing a new, full-screen version of a feed or you’re hearing about it, know that this is a test,” Adam Mosseri said in a video addressing the concerns over the platform’s changes. “It’s a test to a few percentage of people out there, and the idea is that a more full-screen experience, not only for video but for photos, might be a bit more fun and engaging experience. But I also want to be clear, it’s not yet good.”