Interesting, it seems just as smooth on my OnePlus 13. As an app developer I don't see how the Material 3 Expressive UI would cause reduced performance. My only guess is poor usage of the API by developers.
I also agree, supporting both tools seems unnecessary. In my experiences Kotlin multiplatform and compose multiplatform is vastly more enjoyable to write instead of Dart. The development environment alone has also been much easier to get started with using Kotlin multiplatform.