Could you upload a screenshot from your phone? Searching images online I see plenty that roughly match the colors they're using on the video/website, but none as dark as your iPhone. Reference: https://i.imgur.com/PlGjjQg.png

Maybe a personalization option?

Yes. Apparently I turned on the “increase contrast” Accessibility option years ago. I’ll be leaving it on.

The background color of the bubbles changes in a gradient kind of way, depending on their vertical position on screen. That may explain the disparity you're seeing.