While the nuance is important, money from Google is ad money:
- Directing people to Google Search means Firefox users get exposed to ads
- The money given to Firefox was made selling ads
- Google is an ad company
So yes, Google gives Firefox money for political reasons. Made from ads, so they can sell ads, including to Firefox users.
I'm with you on the first one and that's the closest reason why you could call Firefox payment "ad money". But the rest are not too strong. Google makes a lot of non-ad money too, even if it's a smaller portion than ads. You don't call airlines "banks" just because they make all of their money from currency-like "miles", and even fly at a loss [0].
What I want to say is that calling it "ad money" makes Firefox look bad when it shouldn't.
[0] https://www.theatlantic.com/ideas/archive/2023/09/airlines-b...