Flutter allows the developers to use the same language for both layout and backend needs, enjoy higher animation speed, and so on. But, Flutter is lagging much behind in the market compared to Kotlin. The main reason for this is that Kotlin multiplatform code compiles exactly in the format as that of the targeted platform. Hence, in terms of comparison between Flutter vs Kotlin, the latter is the winner.
According to the StackShare community, Kotlin is listed among the tech stacks by 268 companies and 210 developers and Flutter is mentioned as a technology stack by 42 companies and 146 developers.
You can watch this video on Kotlin vs Flutter to understand more: