使用is_tax 而不是is_category, 和更新get_ancestors 要从查询的对象获取分类，请执行以下操作：

add_filter( \'body_class\', \'custom_cat_archiev_class\' );
function custom_cat_archiev_class( $classes ) {
    if ( is_tax( [\'custom_tax_1\', \'custom_tax_2\'] ) ) {
        $term = get_queried_object();
        $ancestors = get_ancestors( $term->term_id, $term->taxonomy, \'taxonomy\' );
        $classes[] = \'catlevel-\' . ( count( $ancestors ) + 1 );
    }
    return $classes;
}