diff --git a/core/lib/Drupal/Core/Block/Plugin/Block/PageTitleBlock.php b/core/lib/Drupal/Core/Block/Plugin/Block/PageTitleBlock.php
index fa30909..7ff4c2c 100644
--- a/core/lib/Drupal/Core/Block/Plugin/Block/PageTitleBlock.php
+++ b/core/lib/Drupal/Core/Block/Plugin/Block/PageTitleBlock.php
@@ -9,7 +9,6 @@
 
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Block\TitleBlockPluginInterface;
-use Drupal\Core\Form\FormStateInterface;
 
 /**
  * Provides a block to display the page title.
diff --git a/core/lib/Drupal/Core/Block/TitleBlockPluginInterface.php b/core/lib/Drupal/Core/Block/TitleBlockPluginInterface.php
index ee3dd7c..19ab275 100644
--- a/core/lib/Drupal/Core/Block/TitleBlockPluginInterface.php
+++ b/core/lib/Drupal/Core/Block/TitleBlockPluginInterface.php
@@ -22,8 +22,8 @@
    * Sets the title.
    *
    * @param string|array $title
-   *   The page title: either a string for plain titles or a #markup render
-   *   array for formatted titles.
+   *   The page title: either a string for plain titles or a render array for
+   *   formatted titles.
    */
   public function setTitle($title);
 
diff --git a/core/lib/Drupal/Core/Render/Element/PageTitle.php b/core/lib/Drupal/Core/Render/Element/PageTitle.php
index 64ff962..27fbf45 100644
--- a/core/lib/Drupal/Core/Render/Element/PageTitle.php
+++ b/core/lib/Drupal/Core/Render/Element/PageTitle.php
@@ -22,8 +22,8 @@ class PageTitle extends RenderElement {
   public function getInfo() {
     return [
       '#theme' => 'page_title',
-      // The page title: either a string for plain titles or a #markup render
-      // array for formatted titles.
+      // The page title: either a string for plain titles or a render array for
+      // formatted titles.
       '#title' => NULL,
     ];
   }
diff --git a/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php b/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php
index d83c2ca..e54f9c1 100644
--- a/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php
+++ b/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php
@@ -183,8 +183,8 @@ public function providerBuild() {
           'block3' => [],
           '#sorted' => TRUE,
         ],
-        // The main content, messages and title are rendered via the fallback in case
-        // there are no blocks rendering them.
+        // The main content, messages and title are rendered via the fallback in
+        // case there are no blocks rendering them.
         'content' => [
           'system_main' => [
             '#markup' => 'Hello kittens!',
diff --git a/core/modules/system/src/Tests/Update/PageTitleConvertedIntoBlockUpdateTest.php b/core/modules/system/src/Tests/Update/PageTitleConvertedIntoBlockUpdateTest.php
index a81af6e..8051168 100644
--- a/core/modules/system/src/Tests/Update/PageTitleConvertedIntoBlockUpdateTest.php
+++ b/core/modules/system/src/Tests/Update/PageTitleConvertedIntoBlockUpdateTest.php
@@ -57,10 +57,20 @@ public function testUpdateHookN() {
     // We finished updating so we can login the user now.
     $this->drupalLogin($this->rootUser);
 
+    $page = Node::create([
+      'type' => 'page',
+      'title' => 'Page node',
+    ]);
+    $page->save();
+
     // Page title is visible on the home page.
     $this->drupalGet('/node');
     $this->assertRaw('page-title');
 
+    // Page title is visible on a node page.
+    $this->drupalGet('node/' . $page->id());
+    $this->assertRaw('page-title');
+
     $this->drupalGet('admin/structure/block/list/bartik');
 
     /** @var \Drupal\Core\Config\StorageInterface $config_storage */
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 0852d39..5d33780 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -1694,6 +1694,7 @@ function system_update_8008() {
         ] + $page_title_default_settings;
         _system_update_create_block($name, $theme_name, $values);
         break;
+
       case 'classy':
         $name = 'block.block.classy_page_title';
         $values = [
@@ -1702,11 +1703,12 @@ function system_update_8008() {
         ] + $page_title_default_settings;
         _system_update_create_block($name, $theme_name, $values);
         break;
+
       default:
         $custom_themes_installed = TRUE;
-        $name = sprintf('block.block.%s_page_title', $theme_name);
+        $name = 'block.block.{$theme_name}_page_title';
         $values = [
-          'id' => sprintf('%s_page_title', $theme_name),
+          'id' => '{$theme_name}_page_title',
           'region' => 'content',
           'weight' => '-50',
         ] + $page_title_default_settings;
diff --git a/core/themes/bartik/templates/page-title.html.twig b/core/themes/bartik/templates/page-title.html.twig
index 73e4acc..e061cd2 100644
--- a/core/themes/bartik/templates/page-title.html.twig
+++ b/core/themes/bartik/templates/page-title.html.twig
@@ -11,8 +11,6 @@
  * - title: The page title, for use in the actual content.
  * - title_suffix: Additional output populated by modules, intended to be
  *   displayed after the main title tag that appears in the template.
- *
- * @ingroup themeable
  */
 #}
 {% set title_attributes = title_attributes.addClass('title') %}
diff --git a/core/themes/classy/templates/content/page-title.html.twig b/core/themes/classy/templates/content/page-title.html.twig
index 1229bec..adec853 100644
--- a/core/themes/classy/templates/content/page-title.html.twig
+++ b/core/themes/classy/templates/content/page-title.html.twig
@@ -12,8 +12,6 @@
  *   displayed after the main title tag that appears in the template.
  *
  * @see template_preprocess_page_title()
- *
- * @ingroup themeable
  */
 #}
 {{ title_prefix }}