Well, there's the public known facts and then there's a "rumor". I don't know why we're even discussing something as unsubstantiated as the latter.

Besides, even if the price was public, one could read anything it wants it that. "Oh the number is low because MS undermined them".

From what I've seen, the numbers for those companies like Xamarin are always much much lower that BS inflated unicorns with no actual business models...

And there's another thing: for what Xamarin offers (which is in the mobile space, with their support for iOS/Android APIs etc), the open source CLR and the VS Code, the basis for the rumor, don't even figure at all. Nobody that used Xamarin will gonna turn to those products, because they simply don't do the same thing at all.