Illustration: Tiffany Herring/AxiosAppsFlyer has raised more than $1 billion in Series E funding at a $2.7 billion post-money valuation, Axios has learned from sources familiar with the financing.Why it matters: The investment is from four of the world's top advertising platforms, which are betting on the need for independent measurement as AI reshapes digital advertising.Driving the news: Moloco, Google, Meta and Unity have each acquired a minority stake in AppsFlyer, CEO and co-founder Oren Ka...