It looks like that you’re using Androidx version of the extension.
Are you using this one?
https://github.com/vknow360/VerticalViewPager/blob/main/aix/com.sunny.viewpager.aix
If yes then you should use this version in kodular
https://github.com/vknow360/VerticalViewPager/blob/main/aix/com.sunny.viewpager-kodular.aix