I am not sure I'd call this new, because I believe I've seen this numerous times before, but Google has two AI Overview rendering animations. One for when you are not logged into Search Labs and the other for when you are just using normal Google Search with normal AI Overviews.
This was covered via 9to5Google after some Reddit thread posted about this. But I do think the Search Labs experimental AI Overviews version had this rendering for some time (I can be wrong).
Here is the slower test version of the AI Overviews animation as a GIF:
Here is a static image I captured:
Here is the normal one, that is much snappier and way faster (I even had to slow down the GIF so you can see it better):
Google wants these AI Overviews to be lightening speed, so just keep that in mind.
Forum discussion at Reddit.