Google seems to be testing highlighting portions of text in the search result snippets. This seems different from the highlighting of featured snippets, people also ask, things to know or sections of the explore feature. This is Google using blue highlight on the normal search results snippets.
This was spotted by Jonas Sickler who posted the following screenshot on X:
I personally cannot replicate this but Jonas said, "Google is highlighting parts of the descriptions in blue for the first 10 search results." "I did this search on mobile. Also, the "descriptions" under the links in the SERP are like mini featured snippets defining the KW. They aren't the meta descriptions. When you click the text, it takes you directly to the highlighted text like a featured snippet would," he added.
Again, it is not uncommon to see this for featured snippets and friends but for the main search results snippets, this is not common.
Forum discussion at X.
Update: Also for ads:
Just Spotted!
— Anthony Higman (@AnthonyHigman) November 29, 2023
Google Now Including Green Highlighted Text In Ads. #ppcchat pic.twitter.com/4qaSqB8vbC