Javascript
For mobile with React: no AOT compile. Relies on loading the entire JS VM which adds startup time and can require bundling a large library on Android. Cannot easily author customized components that render at native speeds.
C#
For mobile with Xamarin: No hot reload. Dart having its origin as a JS interpreted language had the foundations to be both dynamic and AOT. C# might not ever achieve this?
Kotlin, Java, Swift, Objective C:
Not cross platform.
C++:
Is cross platform. No hot reload. Very unfriendly to modern development and fast iteration.
I don't actively work in mobile. I just like following developments in language technologies, so correct me if I'm wrong.