I have the same issue... purchased through Google and the app says "Windy".

For the record under my billing it says Windy.app: worldwide wind and weather forecast.
WINDY PRO account - annual $49.99/ year.

Just a thought, this is obviously something that has been happening for a while so perhaps letting potential users know that there are other "Windy" apps out there?

Im going back to PredictWind