https://github.com/flutter/flutter/issues/18345#issuecomment-1177751219

custom_sliver_persistent_header.dart

class CustomSliverPersistentHeader extends SingleChildRenderObjectWidget {
  const CustomSliverPersistentHeader({
    super.key,
    required super.child,
  });

  @override
  RenderObject createRenderObject(BuildContext context) =>
      _RenderCustomSliverPersistentHeader();
}

class _RenderCustomSliverPersistentHeader
    extends RenderSliverPinnedPersistentHeader {
  @override
  double get maxExtent =>
      child!.getMaxIntrinsicHeight(constraints.crossAxisExtent);

  @override
  double get minExtent => 0;
}