Getting parent object_id of child menu items in WordPress menu

I made 2 mistakes in my comment.
try rather this code

function data_attribs_menu( $atts, $item, $args ) {
    // check if ACF exists
    if( class_exists('acf') ) {     

        $page_section = get_field( 'page_section', $item->object_id );

        if( $args->theme_location == 'header-menu' ) {
            if( $item->menu_item_parent == 0 ) {
                $atts['data-color'] = $page_section;
            } else {
                $parentItem = get_post($item->menu_item_parent);
                $parent_page_section = get_field( 'page_section', $parentItem->_menu_item_object_id);

                $atts['data-color'] = $parent_page_section;
            }
        }

    }

    return $atts;
}
add_filter('nav_menu_link_attributes', 'data_attribs_menu', 10, 3);

this code only works when there is 2 levels of menu and according the example in the question, it’s what you need.