Google Maps: Circle Pin Instead Of Marker Pin

I am not sure if this is new or happens on some queries but Besian Sopa posted on Twitter a screen shot of a Google Maps Local knowledge panel showing a circle in the map versus showing the typical marker pin icon.

Here is a screen shot from Besian who where we see the circle pin:

Here is a typical look for the marker pin in that knowledge panel:

When does Google show the circle version?

Forum discussion at Twitter.

Mike Blumenthal said on Twitter that the circle happens when it's a SAB and address is hidden.