Does have any suggestion on Should I learn flutter or kotlin?
If you want to develop mobile apps then its better to go with Flutter and Dart.Using kotlin is also officially supported for Android development but very complicated for ios development.
It’s all depends on your choice as both are completely different from each other.
Flutter is hybrid framework that you can used to develop app for multiple platforms from same source code and their performance almost like native app.
Kotlin only used to develop native android app. With kotlin you can develop any complex app where with flutter may find difficult.
Kotlin native features support are better then flutter.
If you looking to be a developer that can develop platform across platforms then go with flutter or if want be android developer then kotlin you should go.