diff -u b/modules/payment/src/Form/PaymentMethodEditForm.php b/modules/payment/src/Form/PaymentMethodEditForm.php
--- b/modules/payment/src/Form/PaymentMethodEditForm.php
+++ b/modules/payment/src/Form/PaymentMethodEditForm.php
@@ -19,7 +19,11 @@
       '#operation' => 'edit-payment-method',
       '#default_value' => $this->entity,
     ];
-
+    /** @var \Drupal\commerce_payment\Entity\PaymentMethod $payment_method */
+    $payment_method = $this->entity;
+    if ($js_library = $payment_method->getPaymentGateway()->getPlugin()->getJsLibrary()) {
+      $form['#attached']['library'][] = $js_library;
+    }
     return $form;
   }
 
only in patch2:
unchanged:
--- a/modules/payment/src/Form/PaymentMethodAddForm.php
+++ b/modules/payment/src/Form/PaymentMethodAddForm.php
@@ -82,6 +82,9 @@ class PaymentMethodAddForm extends FormBase implements ContainerInjectionInterfa
       $form = $this->buildPaymentMethodTypeForm($form, $form_state);
     }
     elseif ($step == 'payment_method') {
+      if ($js_library = $payment_gateway->getPlugin()->getJsLibrary()) {
+        $form['#attached']['library'][] = $js_library;
+      }
       $form = $this->buildPaymentMethodForm($form, $form_state);
     }
 
only in patch2:
unchanged:
--- a/modules/payment/src/PluginForm/PaymentMethodAddForm.php
+++ b/modules/payment/src/PluginForm/PaymentMethodAddForm.php
@@ -52,8 +52,6 @@ class PaymentMethodAddForm extends PaymentGatewayFormBase {
       $form['payment_details'] = $this->buildPayPalForm($form['payment_details'], $form_state);
     }
 
-    /** @var \Drupal\commerce_payment\Entity\PaymentMethodInterface $payment_method */
-    $payment_method = $this->entity;
     /** @var \Drupal\profile\Entity\ProfileInterface $billing_profile */
     $billing_profile = $payment_method->getBillingProfile();
     if (!$billing_profile) {