It’s been a long road, getting from there to here. Google announced at the end of 2016 that it would start rolling out a tabbed interface in the Google app – one tab for your feed (previously known as Google Now), and the other for reminders/emails/etc. But then Google only enabled it for a small amount of users, and left it at that for a few months. Then a third tab was added, and even more users received the changed interface.
Google is rolling out the tabbed Google app interface to more users was written by the awesome team at Android Police.