diff -u b/js/paragraphs.js b/js/paragraphs.js
--- b/js/paragraphs.js
+++ b/js/paragraphs.js
@@ -16,7 +16,7 @@
             }
             else {
               $('.paragraphs-content').hide();
-              $('.paragraphs-nested.paragraphs-subform').show();
+              $('.paragraphs-nested.paragraphs-subform > .paragraphs-content').show();
               $('.paragraphs-behavior').show();
             }
           },
diff -u b/src/Plugin/Field/FieldWidget/ParagraphsWidget.php b/src/Plugin/Field/FieldWidget/ParagraphsWidget.php
--- b/src/Plugin/Field/FieldWidget/ParagraphsWidget.php
+++ b/src/Plugin/Field/FieldWidget/ParagraphsWidget.php
@@ -1189,7 +1189,7 @@
         // Validate all enabled behavior plugins.
         $paragraphs_type = $entity->getParagraphType();
         foreach ($paragraphs_type->getEnabledBehaviorPlugins() as $plugin_id => $plugin_values) {
-          $plugin_values->validateBehaviorForm($element['behavior_plugins'][$plugin_id], $form_state);
+          $plugin_values->validateBehaviorForm($element['subform'][$plugin_id], $form_state);
         }
       }
     }
@@ -1245,14 +1245,14 @@
             $paragraphs_entity->set($langcode_key, $form_state->get('langcode'));
           }
         }
-        if (isset($item['behavior_plugins'])) {
+        if (isset($item['subform'])) {
           // Submit all enabled behavior plugins.
           $paragraphs_type = $paragraphs_entity->getParagraphType();
           foreach ($paragraphs_type->getEnabledBehaviorPlugins() as $plugin_id => $plugin_values) {
-            if (!isset($item['behavior_plugins'][$plugin_id])) {
-              $item['behavior_plugins'][$plugin_id] = [];
+            if (!isset($item['subform'][$plugin_id])) {
+              $item['subform'][$plugin_id] = [];
             }
-            $plugin_values->submitBehaviorForm($paragraphs_entity, $item['behavior_plugins'][$plugin_id]);
+            $plugin_values->submitBehaviorForm($paragraphs_entity, $item['subform'][$plugin_id]);
           }
         }
 
only in patch2:
unchanged:
--- a/src/Tests/Experimental/ParagraphsExperimentalBehaviorsTest.php
+++ b/src/Tests/Experimental/ParagraphsExperimentalBehaviorsTest.php
@@ -68,13 +68,13 @@ class ParagraphsExperimentalBehaviorsTest extends ParagraphsExperimentalTestBase
 
     // Create a node with a Paragraph.
     $this->drupalGet('node/add/paragraphed_test');
-    $this->assertFieldByName('field_paragraphs[0][behavior_plugins][test_text_color][text_color]', 'green');
+    $this->assertFieldByName('field_paragraphs[0][subform][test_text_color][text_color]', 'green');
     // Setting a not allowed value in the text color plugin text field.
     $plugin_text = 'green';
     $edit = [
       'title[0][value]' => 'paragraphs_plugins_test',
       'field_paragraphs[0][subform][field_text][0][value]' => 'amazing_plugin_test',
-      'field_paragraphs[0][behavior_plugins][test_text_color][text_color]' => $plugin_text,
+      'field_paragraphs[0][subform][test_text_color][text_color]' => $plugin_text,
     ];
     $this->drupalPostForm(NULL, $edit, t('Save and publish'));
     // Asserting that the error message is shown.
@@ -82,7 +82,7 @@ class ParagraphsExperimentalBehaviorsTest extends ParagraphsExperimentalTestBase
     // Updating the text color to an allowed value.
     $plugin_text = 'red';
     $edit = [
-      'field_paragraphs[0][behavior_plugins][test_text_color][text_color]' => $plugin_text,
+      'field_paragraphs[0][subform][test_text_color][text_color]' => $plugin_text,
     ];
     $this->drupalPostForm(NULL, $edit, t('Save and publish'));
     // Assert that the class has been added to the element.
@@ -90,21 +90,21 @@ class ParagraphsExperimentalBehaviorsTest extends ParagraphsExperimentalTestBase
 
     $this->clickLink('Edit');
     // Assert the plugin fields populate the stored values.
-    $this->assertFieldByName('field_paragraphs[0][behavior_plugins][test_text_color][text_color]', $plugin_text);
+    $this->assertFieldByName('field_paragraphs[0][subform][test_text_color][text_color]', $plugin_text);
 
     // Update the value of both plugins.
     $updated_text = 'blue';
     $edit = [
-      'field_paragraphs[0][behavior_plugins][test_text_color][text_color]' => $updated_text,
-      'field_paragraphs[0][behavior_plugins][test_bold_text][bold_text]' => TRUE,
+      'field_paragraphs[0][subform][test_text_color][text_color]' => $updated_text,
+      'field_paragraphs[0][subform][test_bold_text][bold_text]' => TRUE,
     ];
     $this->drupalPostForm(NULL, $edit, t('Save and keep published'));
     $this->assertNoRaw('class="red_plugin_text');
     $this->assertRaw('class="blue_plugin_text bold_plugin_text');
     $this->clickLink('Edit');
     // Assert the plugin fields populate the stored values.
-    $this->assertFieldByName('field_paragraphs[0][behavior_plugins][test_text_color][text_color]', $updated_text);
-    $this->assertFieldByName('field_paragraphs[0][behavior_plugins][test_bold_text][bold_text]', TRUE);
+    $this->assertFieldByName('field_paragraphs[0][subform][test_text_color][text_color]', $updated_text);
+    $this->assertFieldByName('field_paragraphs[0][subform][test_bold_text][bold_text]', TRUE);
 
     // Test plugin applicability. Add a paragraph type.
     $paragraph_type = 'text_paragraph_test';