For my final test, I need to wait until it's "a time Google thinks I should be awake" in my timezone, because right now my leading theory is that Google is applying their own blue-light-filter by switching into a second THIRD SEARCH SKIN based on the current timezone + location.
And when I log out*/use private browsing/use incognito: it doesn't know my location to personalize it to.
*haven't actually tried logging out, just private modes. I hope that is not an oversight.