Restrict payment gateways based on applied coupons in WooCommerce checkout displaying a message

I would like to only show e.g. Stripe if coupon code 123 is used. So, I have come up with the code which is working, but I would also like to show a message at the top of the checkout, where the woo notices show. My message isn’t showing correctly.

// restrict coupon codes payment method
add_filter('woocommerce_available_payment_gateways', 'unset_gateway_by_applied_coupons');

function unset_gateway_by_applied_coupons($available_gateways) {
    // prevents coupon error in admin
    if( is_admin() ) 
        return $available_gateways;
    
    global $woocommerce;
    $unset = false; // the norm
    
    // names of coupons
    $coupon_codes = array('test123', 'check123');
            
    foreach($coupon_codes as $coupon_code) {
        
        // if code is used in cart
        if(in_array($coupon_code, WC()->cart->get_applied_coupons() )){
            //echo 'found =' .$coupon_code;
            unset($available_gateways['bacs']);
            unset($available_gateways['invoice']);
            // $message = sprintf( __('<br><p class="coupon-code">The coupon code  "%s" can only use the Credit Card payment method.</p>'), $coupon_code);  // <<<<< not working
        }
            
    }
    return $available_gateways;
}