To process field group settings on user register form in checkout pane.

commerce-checkout-user-register-respect-field-group-settings.patch

diff --git a/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php b/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php
index 2bdc785b..b1908d91 100644
--- a/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php
+++ b/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php
@@ -282,6 +282,7 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
       '#type' => 'email',
       '#title' => $this->t('Email address'),
       '#required' => FALSE,
+      '#weight' => -100,
     ];
     $pane_form['register']['name'] = [
       '#type' => 'textfield',
@@ -296,12 +297,14 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
         'spellcheck' => 'false',
       ],
       '#default_value' => '',
+      '#weight' => -99,
     ];
     $pane_form['register']['password'] = [
       '#type' => 'password_confirm',
       '#size' => 60,
       '#description' => $this->t('Provide a password for the new account in both fields.'),
       '#required' => FALSE,
+      '#weight' => -98,
     ];
     $pane_form['register']['register'] = [
       '#type' => 'submit',
@@ -315,6 +318,23 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
     $form_display = EntityFormDisplay::collectRenderDisplay($account, 'register');
     $form_display->buildForm($account, $pane_form['register'], $form_state);
 
+    if (\Drupal::moduleHandler()->moduleExists('field_group')) {
+      $entity = $account;
+
+      $context = [
+        'entity_type' => $entity->getEntityTypeId(),
+        'bundle' => $entity->bundle(),
+        'entity' => $entity,
+        'context' => 'form',
+        'display_context' => 'form',
+        'mode' => $form_display->getMode(),
+      ];
+
+      field_group_attach_groups($pane_form['register'], $context);
+      $pane_form['register']['#process'][] = [\Drupal\field_group\FormatterHelper::class, 'formProcess'];
+      $pane_form['register']['#pre_render'][] = [\Drupal\field_group\FormatterHelper::class, 'formGroupPreRender'];
+    }
+
     return $pane_form;
   }