Google Now was a big deal when it debuted years back, but now Google is all about Assistant. The Google Now pane got its last redesign in 2015, but Google appears to be testing something more radical currently. Some users are starting to see a transparent Google Now pane.
Technically, Google Now doesn't exist anymore. Google Now is currently known as the Google Feed, but everyone still thinks of this home screen panel as Google Now. Maybe a radical redesign will help everyone get used to the new naming. Instead of the completely white background we have now, the new version uses your wallpaper, possibly with a darkened filter. The content appears to be mostly the same, though.
The Redditor who posted the images says he's on an unrooted Pixel XL with the previous month's security patch. We've seen this UI pop up a few times, so this is probably something Google is actually considering as an official UI. It does look cool, but it could be a little hard to read text if you have a busy background.