Noindex canonical

add_action( 'rank_math/head', function() {
    if (is_product_category()){
        $canonical =  RankMath\Paper\Paper::get()->get_canonical();
        $can =  substr($canonical, 0, strpos($canonical, "page"));
        if ( MyThemeShop\Helpers\Str::is_non_empty( $can ) ) {
            echo '<link rel="canonical" href="'. esc_url( $can, null, 'other' ) . '" />' . "\n";
        }
    }
} );