Google Image Search Section For "Top Categorized Results" - Confused?

Google Image search on mobile has these labels for sections of the images it sometimes shows in the search results. A new label I have not seen before is showing "top categorized results." I have no clue what that means - do you?

I mean, I get and understand the latest images section but "top categorized results" - what is that?

I can replicate it myself but here is a screenshot from Saad AK on Twitter of images of broast.

Anyone here have any ideas what this is?

Forum discussion at Twitter.