With the same query, the first 4 responses for me are to the same page but for different Python versions.  None of the URLs include the query string.  `highlight=s` causes all the 's'es in the document to be highlighted, though with a different color than if I hit cntl-F, s, [Highlight All].  Yes, ask Google :-( -- or better yet, let it go as a random 'phase of the moon' AI glitch.  As Google's AI is constantly adjusted and retrained, I would not expect there to every be an exact repeat. There is nothing in your query to suggest that 's'es should be highlighted.