Both Semrush and SimilarWeb's RankRanger tool are reporting that Google is showing fewer sitelinks within the Google Search results. In fact, it seemed to have dropped 10 to 20 percentage points. The drop started on Thursday, March 14th.
What are sitelinks? The links you see under the main search result listing - they can be like larger sitelinks or smaller ones. Here is a screenshot of sitelinks:
Here is what the SimilarWeb tool shows, Sitelinks went from showing 63% to about 41%:
Here is what the Semrush tool shows, Sitelinks went from showing 68% to about 58%:
The Moz tool does not seem to be updated, so I cannot share there data.
Brodie Clark posted on X about it saying, "Google is now showing drastically less sitelinks for pages in Search. From what I can see, this looks to be because of a test where sitelinks aren't showing at all for pages. Good one to keep in mind if we you notice changes in your GSC data."
Forum discussion at X.