Several weeks ago, Google introduced the unified header and got rid of the top navbar that had been adorning Google sites for years. It was a step forward it said, the latest move in a recent drive to update the look and feel of all Google products.
But it seems the move was short-lived, Google is making a tactical retreat or may even be backing down on the whole thing as more
people are noticing that the black navbar is back.
Not all users have been reverted, but clearing the browser cookies is basically guaranteed to bring back the old, black navbar.
It's unclear why Google made this move, it isn't saying anything at this point, but the obvious reason seems to be that it listened to its critics and decided to go back to the drawing board.
The unified header was criticized mostly for the fact that it hid links to Google products. It also turned the Google logo, used to go back to the main page into a menu trigger.