Discount per different user roles

functions.php

<?php

add_filter('gens_raf_coupon_amount','change_coupon_amount',10, 2);
function change_coupon_amount($amount,$order_id){
    // get number of referrals
    $referrer_id = get_post_meta($order_id,'_wpgens_raf_id',true);
    $user = reset(get_users(array('meta_key' => 'gens_referral_id', 'meta_value' => $referrer_id)));
    $roles = $user->roles;
    
    if(in_array('kol', $roles)) {
      return $amount * 3;
    } else if(in_array('koc', $roles)) {
      return $amount * 2;
    }
    
    return $amount;
}