Not messed up; new design.
There is nothing there about exposure either.
Clipping would be shown if there were a spike and there isn't one. The green line simply 'draws a color for the floor' of the Histogram (one might argue it should be white as seen in Lightroom; I'll recommend that in Pre-Release as indeed, green doesn't make as much sense) but in your example, there is no clipping. Plus, the clipping triangle would 'light up' too if clipping shows.
Move Saturation to -100; that green line is now gray but still exists to show this 'floor' of Histogram.
There is no way to set it 'back to normal', this is the new normal.