We've seen a similar format in the Google Shopping results with a show more button to show more shopping ads but now we are seeing something similar within the main Google Search results. Google is testing overlaying a show more button on the second row of Google Shopping ads in the main search results.
We saw this when Google was testing three rows of Shopping Ads in Google Shopping.
Now, Sachin Patel posted images of Google testing something similar in the main Google results. He posted on X this screenshot, which I cannot replicate:
Here is a GIF of it in action:
We've seen see more buttons on Shopping Ads before. We've also seen buttons for more sponsored results but this is a slightly different take on those.
Forum discussion at X.