It's those kind of UI ideas that look great on a mockup, but do not work in reality with real data and real users, those that open 35 tabs—behaviour encouraged by macOS windowing system by the way—and now all of those are crammed into a ludicrously small space that's constantly moving around.
I don't know what Apple were thinking there. Let's not call it UX, this is designers changing for change's sake at the expense of user experience. I'm struggling to see how is it justifiable in any way.