I don't know what frameworks they are using at Square but when I was doing Xamarin development it was absurd how much size/overhead was added to an app, to the point that a simple Hello World app was a few dozen MB while a plain Java (or later: Kotlin) app was a couple MBs. I heard from other mobile devs that excessive bloat from adding any framework or 3rd party libraries was a known issue but devs who can code it all by hand were rare and ultimately clients didn't care as long as they could put an app in the app store (even if it was 99 MB of bloatware).