2018 Upgrade changed my lighting

I updated my project from Unity 2017.4.4 to 2018.2.3.
In the editor, every scene is darker, and looks oddly contrast-y.

BUT when I build to stand-alone exe, everything looks good, like it did before my upgrade.
In the below image, the top is wrong, and the bottom is correct. What do you think is going on in the editor?

(I can post screenshots of other scenes, but many of them are simply very dark).

Thank you.