Add currency code after Direct Stripe donation input field

ds-currency-code.php

<?php
/*
 * Plugin Name: DS currency code
 * Description: Add currency code after Direct Stripe donation input field
 * Version:     0.0.1
 * Author:      Nicolas Figueira
 * Author URI:  https://newo.me
 */
add_filter( 'direct_stripe_donation_input', function( $direct_stripe_donation_input, $instance, $button_id ) {
  if( $button_id === 'euros-button' ){ // Edit with the CSS ID of button in euros
    $text = 'EUR';
  } else if( $button_id === 'usd-button' ){ // Edit with the CSS ID of button in usd
    $text= 'USD';
  }
  $direct_stripe_donation_input .= '<span class="curency-info"> ' . $text . '</span>';
  
  return $direct_stripe_donation_input;
}, 10, 3);