Google is testing a user interface where it does not surround a knowledge panel completely with a box. Instead, there is just this vertical divider line in the desktop results.

Frank Sandtmann, a German based SEO, notified me of this and I can replicate it in some browsers. So this 100% looks like some sort of minimalistic test.

Here is a screenshot of the knowledge panel with just the vertical line (click to enlarge):

Here is a screenshot of the knowledge panel with like it normally is, boxed in (click to enlarge):

I prefer the vertical line, I think.

Forum discussion at Twitter.