Screenshots of the UI changes on the Mac - in my opinion it is now just wasting a lot of screen estate for zero benefit.
On non-Macs they’re adding an extra usability issue by hiding the top menu bar. I’ve gove back to 2.7.4 for now - fortunately I had my configuration in git.
Up to 2.7.4:
2.8.4:
To my knowledge the only way to “turn off” the menu bar is to run a program in full screen mode on a mac.