Discount for specific shipping methods in WooCommerce checkout

I like to give a discount on some Local Pickup shipping methods. With the code below, I get a discount on all shipping methods (including also Flat Rate and Free Shipping).

But I would like this discount to be applied only on some specific Local Pickup shipping methods I have defined here below in my code:

add_action( 'woocommerce_cart_calculate_fees', 'custom_discount_for_pickup_shipping_method', 10, 1 );
function custom_discount_for_pickup_shipping_method( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // Only on checkout page
    if ( is_checkout() ) {
    
        $percentage = 5; // <=== Discount percentage
    
        $chosen_shipping_method_id = WC()->session->get( 'chosen_shipping_methods' )[0];
        $chosen_shipping_method    = explode(':', $chosen_shipping_method_id)[0];
    
        // Only for Local pickup chosen shipping method
        if ( strpos( $chosen_shipping_method_id, 'local_pickup:63', 'local_pickup:64', 'local_pickup:65', 'local_pickup:66', 'local_pickup:67', 'local_pickup:68', 'local_pickup:69' ) !== false ) {
            // Calculate the discount
            $discount = $cart->get_subtotal() * $percentage / 100;
            // Add the discount
            $cart->add_fee( __('3% afhaalkorting, levering vanuit ons magazijn') . ' (' . $percentage . '%)', -$discount );
        }
    }
}

First in WooCommerce you can have multiple shipping methods applied on a split cart, so an array of shipping methods.

Here you are trying to apply a discount from some Local Pickup shipping methods, so from an other array of defined shipping methods.

In this case is better to use the functions array_intersect() in an IF statement, this way:

add_action( 'woocommerce_cart_calculate_fees', 'custom_discount_for_pickup_shipping_methods', 10, 1 );
function custom_discount_for_pickup_shipping_methods( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // Only on checkout page
    if ( is_checkout() ) {
        
        // Here below define your allowed shipping methods rate Ids in this array
        $allowed_shipping_methods = array('local_pickup:63', 'local_pickup:64', 'local_pickup:65', 'local_pickup:66', 'local_pickup:67', 'local_pickup:68', 'local_pickup:69');
        
        $chosen_shipping_methods = WC()->session->get( 'chosen_shipping_methods' );
    
        // Only for Local pickup chosen shipping method
        if ( count( array_intersect($allowed_shipping_methods, $chosen_shipping_methods) ) > 0 ) {
            // Discount percentage
            $percentage = 5;
            // Calculate discount
            $discount = $cart->get_subtotal() * $percentage / 100;
            // Add the discount
            $cart->add_fee( $percentage . __('% afhaalkorting, levering vanuit ons magazijn'), -$discount );
        }
    }
}

Code goes in functions.php file of your active child theme (or active theme). Tested and works.