Working with sliver app bar

[JanHitako]

Does anyone know how to make this work under a sliver app bar?

With this setup, the tab-bar just fall behind the appbar (overlapping) when we scroll down instead of staying below it:

NestedScrollView(
        headerSliverBuilder: (_, _) => [
          SliverAppBar(
              pinned: true,
              expandedHeight: 150,
              ...
                ),
              ])
        ],
        body: DynamicTabBarWidget( 
        ....
             CustomScrollView down somewhere in the tree
        ....

Thank you.