Google Search is testing horizontal lines under the sitelinks and the people also ask elements in the search results. This is a long horizontal line that goes across the while search result snippet. Google is also testing this darker line for featured snippets.

Also, Google is testing rounded sitelink buttons.

This was spotted by both Brodie Clark on X and Will O’Hara on X. Here are Will’s screenshots:

Sitelinks:

People also ask:

Google is also testing rounded sitelinks again via Brodie Clark.

Here are more screenshots:

This is the featured snippet example:

Forum discussion at X.