This could cause some headaches for social media managers - Facebook's testing out a new image size option for link previews which would alter the presentation of content in the News Feed.
We asked Facebook about it, and they confirmed that this is part of a test with a "small percentage of users". The test, Facebook says, involves users seeing images in 1x1 format rather than landscape. At this stage, Facebook says it has no plans to roll it out more broadly.
Original source: https://www.socialmediatoday.com/