Comment by pjmlp

Google is surely pumping lots of money into Kotlin, had it not been for them, and Kotlin would just be yet another runner up in the long list of JVM guest languages.

It is also due to Android Studio performance issues that Kotlin compiler improvements came to be, and also the compiler plugins for stuff like kapt and Jetpack Composer.

Android Java might be stagnant, not kept up to date with standard Java, yet it still rules in Studio tooling performance.