https://note.com/kitoko552/n/n7da7c55ebab6

note_n7da7c55ebab6_3.dart

Scaffold(
 appBar: AppBar(title: const Text('Books'), elevation: 0.0), // ScaffoldのappBarに普通のAppBarをセット
 body: DefaultTabController(
   length: _tabs.length,
   child: NestedScrollView(
     headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
       return <Widget>[
         // SliverAppBarを削除
       ];
     },
     body: TabBarView(),
   ),
 ),
);