Google is testing a new feature for featured snippets that will animate the highlighting of the text of part of the featured snippet. It looks like Google is manually highlighting the text in the featured snippet.
This was spotted by Shameem Adhikarath who shared a video screen recording of this in action on X - here is a GIF of that video:
I personally cannot replicate this, can you?
The CSS code has "animation: 0.75s highlight 0.25s l normal forwards" called in it.
— Shameem Adhikarath (@shemiadhikarath) February 9, 2024
Forum discussion at X.