“ Is available in Flutter, React-Native & Kotlin Multi-platform for cross-platform developers, since most apps are built with these today.”

Is this really true? Where are these stats coming from?

Probably they mean new apps. Since kotlin multiplatform on android is just native android and android share is like 70% if devices it already at least 50% market share of mobile apps. If you add flutter and react native there is not much left: only games like unity and unreal. I see much less iOS jobs these days.