It is rerolling of patch https://www.drupal.org/project/commerce/issues/3328849#comment-14850565 to apply over other patches already applied there.

3328849-3-wwm-modified.patch

diff --git a/modules/checkout/config/schema/commerce_checkout.schema.yml b/modules/checkout/config/schema/commerce_checkout.schema.yml
index 95d17db5..2acd96eb 100644
--- a/modules/checkout/config/schema/commerce_checkout.schema.yml
+++ b/modules/checkout/config/schema/commerce_checkout.schema.yml
@@ -78,6 +78,9 @@ commerce_checkout.commerce_checkout_pane.login:
     register_form_title:
       type: string
       label: 'Title For New Customer Form'
+    register_form_mode:
+      type: string
+      label: 'Register Form Mode'
 
 commerce_checkout.commerce_checkout_pane.order_summary:
   type: commerce_checkout_pane_configuration
diff --git a/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php b/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php
index 2e41aae8..3d450889 100644
--- a/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php
+++ b/modules/checkout/src/Plugin/Commerce/CheckoutPane/Login.php
@@ -127,6 +127,7 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
       'allow_registration' => FALSE,
       'returning_customer_form_title' => '',
       'register_form_title' => '',
+      'register_form_mode' => 'register',
     ] + parent::defaultConfiguration();
   }
 
@@ -181,6 +182,18 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
       '#title' => $this->t('Title For New Customer Form'),
       '#default_value' => $this->configuration['register_form_title'],
     ];
+    $form_modes = \Drupal::service('entity_display.repository')
+      ->getFormModes('user');
+    $form_mode_options = [];
+    foreach ($form_modes as $form_mode_id => $form_mode) {
+      $form_mode_options[$form_mode_id] = $form_mode['label'];
+    }
+    $form['register_form_mode'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Register Form Mode'),
+      '#default_value' => $this->configuration['register_form_mode'],
+      '#options' => $form_mode_options,
+    ];
 
     return $form;
   }
@@ -197,6 +210,7 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
       $this->configuration['allow_registration'] = !empty($values['allow_registration']);
       $this->configuration['returning_customer_form_title'] = $values['returning_customer_form_title'];
       $this->configuration['register_form_title'] = $values['register_form_title'];
+      $this->configuration['register_form_mode'] = $values['register_form_mode'];
     }
   }
 
@@ -332,7 +346,7 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
 
     /** @var \Drupal\user\UserInterface $account */
     $account = $this->entityTypeManager->getStorage('user')->create([]);
-    $form_display = EntityFormDisplay::collectRenderDisplay($account, 'register');
+    $form_display = EntityFormDisplay::collectRenderDisplay($account, $this->configuration['register_form_mode']);
     $form_display->buildForm($account, $pane_form['register'], $form_state);
 
     if (\Drupal::moduleHandler()->moduleExists('field_group')) {
@@ -429,7 +443,7 @@ class Login extends CheckoutPaneBase implements CheckoutPaneInterface, Container
           'preferred_admin_langcode' => $this->languageManager->getCurrentLanguage()->getId(),
         ]);
 
-        $form_display = EntityFormDisplay::collectRenderDisplay($account, 'register');
+        $form_display = EntityFormDisplay::collectRenderDisplay($account, $this->configuration['register_form_mode']);
         $form_display->extractFormValues($account, $pane_form['register'], $form_state);
         $form_display->validateFormValues($account, $pane_form['register'], $form_state);