We've seen Google group snippets but now Google is testing that the first snippet in the group has a larger font size for the title. This was spotted by both Brodie Clark and Brian Freiesleben and posted on Twitter.
Here is the normal version:
Here are some more examples:
Have been seeing that test on and off for the past week. Same applies to the first Ad too. Is an interesting one. Couple of screenshots here: https://t.co/pZPb0ATj9y— Brodie Clark (@brodieseo) May 26, 2020