Google Undisclosed Blue Search Answer?

I am not sure what this is but Google is testing (or maybe it is a bug) an answer box of sorts, in a blue highlight background (grayish on dark mode) with an answer. But there is no label on the result, is it an AI Overview, featured snippet or some other box?

I was first notified of this by David Matthew Kongsdorf Larsen (check out his YouTube channel) who send me this screenshot:

So I asked if anyone else have seen this before on X and some others responded:

Yes https://t.co/RZEHi9Ex4t

— Deepak Yadav (@deepaksgt) June 23, 2025

Yes, yesterday at 8 p.m. Paris time.

With a small HTML tag bug. pic.twitter.com/emFS9pKv15

— Damien (andell) (@AndellDam) June 23, 2025

Brodie Clark was able to trigger this and shared a video of it in action on X and SERP Alerts:

I am not sure what this is.

Forum discussion at X.

Update: Nate notified me of this back on June 4th and I missed it:

So... is this an ad in AiOverviews or is this AiOverviews? Either way, I haven't seen one with a blue background. Reminds me of Google Ads back in 2008! #ppcchat #ICYMI #googleads #aioverviews pic.twitter.com/986ZwnMNvi

— Nate Louis (@N8Louis) June 4, 2025