
"I know some of you really like your squares. And square photos are sort of the heritage of Instagram," Instagram chief Adam Mosseri said in an Instagram story. "But at this point, most of what’s uploaded, both photos and videos, are vertical in their orientation. And it just is a bummer to overly crop them. I know it's a change. I know it's a bit of a pain, but I think it's a transitional pain."
https://mashable.com/article/instagram-rectangle-square-grid