Different regions use different ingredients for Coke, so I guess it’s possible this is true in your region, but my coke can in California doesn’t appear to list Vanilla in its ingredients.
Additionally, there was this lawsuit about Vanilla Orange Coke containining vanillin, which leads me to think it’s unlikely there’s much Vanilla Bean involved in non-Vanilla Coke, at least:
https://www.classaction.org/news/fake-vanilla-coca-cola-comp...
With that said, numbers like 99% of vanilla being from vanillin does sound like a made up statistic.