UPDATE: Instagram fixed the "bug" saying it was a mistake and just supposed to be a test. Sure. Likely story. Seems like you probably changed it and people were pissed so you changed it back and tried to be like "oops!" WE ARE ONTO YOU, INSTAGRAM
I'm basically reporting live from my phone right now and I AM SHOOK. Opened up Instagram, went to scroll (as you do), and lo and behold, it tells me I basically have to swipe across instead of scroll up and down. It's like a one post per page thing. Like Tinder.
Why, insta? Why would you do this? No one asked for this. It's harder to navigate. It's not fun.
You're on thin ice, insta. THIN. ICE.
Read all about the update here. Or just open the app.