woocommerce_additional_shipping_fee.php

<?php

//additional_shipping_fee
//add_action( 'woocommerce_cart_calculate_fees', 'bbloomer_add_cart_fee' );
 
function bbloomer_add_cart_fee() {

 $surcharge = 2; // 5% surcharge based on shipping cost
 WC()->cart->add_fee( __('Handling', 'woocommerce'), $surcharge );

}

add_filter('woocommerce_package_rates', 'custom_shipping_costs', 10, 2 );
function custom_shipping_costs( $rates, $package ){
    
    
    $items = WC()->cart->get_cart();
    $price = 0;
        foreach($items as $item => $values) { 
            $additional = get_post_meta($values['product_id'] , 'additional_shipping_fee', true);
           
            if(!empty($additional) ){
                $price  = $price + $additional;
            }
            
        
        } 
        
        
    // Loop through shipping methods rates
    foreach ( $rates as $rate_key => $rate ){
         // Targeting all shipping methods except "Free shipping"
        if ( 'free_shipping' !== $rate->method_id ) {
            $has_taxes = false;
            $taxes = [];
            $rates[$rate_key]->cost = $price + $rates[$rate_key]->cost ;
          
            // Taxes rate cost (if enabled)
            foreach ($rates[$rate_key]->taxes as $key => $tax){
                if( $tax > 0 ){
                    $has_taxes = true;
                    $taxes[$key] = 0; // Set to 0 (zero)
                }
            }
            if( $has_taxes )
                $rates[$rate_key]->taxes = $taxes;
        }
    }
    return $rates;
}

?>