[satvikpendem]

Well, Flutter is primarily for apps that work cross platform, if you use Kotlin then you can only run it on Android (yes, Kotlin Multiplatform with Compose Multiplatform exist but they're even less mature than Flutter).

For JS/TS, you could use React Native but you also wouldn't get the full spread of platforms as RN is primarily for mobile and the web and desktop implementations are based on third-party support, plus the developer experience is inferior to Flutter.

So, if you want to make multiplatform apps, use Flutter, but if you only need to make Android or RN apps, use those respective platform tools.