diff --git a/core/lib/Drupal/Core/Datetime/Element/Datetime.php b/core/lib/Drupal/Core/Datetime/Element/Datetime.php
index 9a83720565..d54e24e5e4 100644
--- a/core/lib/Drupal/Core/Datetime/Element/Datetime.php
+++ b/core/lib/Drupal/Core/Datetime/Element/Datetime.php
@@ -5,8 +5,8 @@
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Component\Utility\Variable;
 use Drupal\Core\Datetime\DrupalDateTime;
-use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Datetime\Entity\DateFormat;
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Security\DoTrustedCallbackTrait;
 use Drupal\Core\Security\StaticTrustedCallbackHelper;
 
@@ -239,7 +239,6 @@ public static function processDatetime(&$element, FormStateInterface $form_state
       // placeholders are invalid for HTML5 date and datetime, so an example
       // format is appended to the title to appear in tooltips.
       $extra_attributes = [
-        'title' => t('Date (e.g. @format)', ['@format' => static::formatExample($date_format)]),
         'type' => $element['#date_date_element'],
       ];
 
@@ -285,7 +284,6 @@ public static function processDatetime(&$element, FormStateInterface $form_state
 
       // Adds the HTML5 attributes.
       $extra_attributes = [
-        'title' => t('Time (e.g. @format)', ['@format' => static::formatExample($time_format)]),
         'type' => $element['#date_time_element'],
         'step' => $element['#date_increment'],
       ];
@@ -352,9 +350,6 @@ public static function validateDatetime(&$element, FormStateInterface $form_stat
     if ($input_exists) {
 
       $title = static::getElementTitle($element, $complete_form);
-      $date_format = $element['#date_date_element'] != 'none' ? static::getHtml5DateFormat($element) : '';
-      $time_format = $element['#date_time_element'] != 'none' ? static::getHtml5TimeFormat($element) : '';
-      $format = trim($date_format . ' ' . $time_format);
 
       // If there's empty input and the field is not required, set it to empty.
       if (empty($input['date']) && empty($input['time']) && !$element['#required']) {
@@ -363,7 +358,7 @@ public static function validateDatetime(&$element, FormStateInterface $form_stat
       // If there's empty input and the field is required, set an error. A
       // reminder of the required format in the message provides a good UX.
       elseif (empty($input['date']) && empty($input['time']) && $element['#required']) {
-        $form_state->setError($element, t('The %field date is required. Enter a date in the format %format.', ['%field' => $title, '%format' => static::formatExample($format)]));
+        $form_state->setError($element, t('The %field date is required.', ['%field' => $title]));
       }
       else {
         // If the date is valid, set it.
@@ -374,29 +369,12 @@ public static function validateDatetime(&$element, FormStateInterface $form_stat
         // If the date is invalid, set an error. A reminder of the required
         // format in the message provides a good UX.
         else {
-          $form_state->setError($element, t('The %field date is invalid. Enter a date in the format %format.', ['%field' => $title, '%format' => static::formatExample($format)]));
+          $form_state->setError($element, t('The %field date is invalid. Enter a date in the correct format.', ['%field' => $title]));
         }
       }
     }
   }
 
-  /**
-   * Creates an example for a date format.
-   *
-   * This is centralized for a consistent method of creating these examples.
-   *
-   * @param string $format
-   *   The date format.
-   *
-   * @return string
-   */
-  public static function formatExample($format) {
-    if (!static::$dateExample) {
-      static::$dateExample = new DrupalDateTime();
-    }
-    return static::$dateExample->format($format);
-  }
-
   /**
    * Retrieves the right format for an HTML5 date element.
    *
diff --git a/core/lib/Drupal/Core/Datetime/Plugin/Field/FieldWidget/TimestampDatetimeWidget.php b/core/lib/Drupal/Core/Datetime/Plugin/Field/FieldWidget/TimestampDatetimeWidget.php
index 0ebe7b52d5..af3fd0dcee 100644
--- a/core/lib/Drupal/Core/Datetime/Plugin/Field/FieldWidget/TimestampDatetimeWidget.php
+++ b/core/lib/Drupal/Core/Datetime/Plugin/Field/FieldWidget/TimestampDatetimeWidget.php
@@ -3,8 +3,6 @@
 namespace Drupal\Core\Datetime\Plugin\Field\FieldWidget;
 
 use Drupal\Core\Datetime\DrupalDateTime;
-use Drupal\Core\Datetime\Element\Datetime;
-use Drupal\Core\Datetime\Entity\DateFormat;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Field\WidgetBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -27,9 +25,8 @@ class TimestampDatetimeWidget extends WidgetBase {
    * {@inheritdoc}
    */
   public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
-    $date_format = DateFormat::load('html_date')->getPattern();
-    $time_format = DateFormat::load('html_time')->getPattern();
-    $default_value = isset($items[$delta]->value) ? DrupalDateTime::createFromTimestamp($items[$delta]->value) : '';
+    $parent_entity = $items->getParent()->getValue();
+    $default_value = (!$parent_entity->isNew() && isset($items[$delta]->value)) ? DrupalDateTime::createFromTimestamp($items[$delta]->value) : '';
     $element['value'] = $element + [
       '#type' => 'datetime',
       '#default_value' => $default_value,
@@ -38,9 +35,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
 
     $element['value']['#description'] = $element['#description'] !== ''
     ? $element['#description']
-    : $this->t('Format: %format. Leave blank to use the time of form submission.',
-    ['%format' => Datetime::formatExample($date_format . ' ' . $time_format)]);
-
+    : $this->t('Leave blank to use the time of form submission.');
     return $element;
   }
 
diff --git a/core/modules/content_translation/src/ContentTranslationHandler.php b/core/modules/content_translation/src/ContentTranslationHandler.php
index d3dad8ee80..b4911b60af 100644
--- a/core/modules/content_translation/src/ContentTranslationHandler.php
+++ b/core/modules/content_translation/src/ContentTranslationHandler.php
@@ -541,10 +541,7 @@ public function entityFormAlter(array &$form, FormStateInterface $form_state, En
         '#type' => 'textfield',
         '#title' => t('Authored on'),
         '#maxlength' => 25,
-        '#description' => t('Format: %time. The date format is YYYY-MM-DD and %timezone is the time zone offset from UTC. Leave blank to use the time of form submission.', [
-          '%time' => $this->dateFormatter->format(REQUEST_TIME, 'custom', 'Y-m-d H:i:s O'),
-          '%timezone' => $this->dateFormatter->format(REQUEST_TIME, 'custom', 'O'),
-        ]),
+        '#description' => t('Leave blank to use the time of form submission.'),
         '#default_value' => $new_translation || !$date ? '' : $this->dateFormatter->format($date, 'custom', 'Y-m-d H:i:s O'),
       ];
 
diff --git a/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php b/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php
index 797cdc6803..7dd0eaed5c 100644
--- a/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php
+++ b/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php
@@ -393,12 +393,9 @@ public function testDatetimeField() {
     $form_state = new FormState();
     \Drupal::formBuilder()->submitForm($form, $form_state);
     $errors = $form_state->getErrors();
-    $arguments = $errors["{$field_name}][0][value"]->getArguments();
-    $expected_error_message = new FormattableMarkup('The %field date is required. Enter a date in the format %format.', ['%field' => $field_label, '%format' => $arguments['%format']]);
+    $expected_error_message = new FormattableMarkup('The %field date is required.', ['%field' => $field_label]);
     $actual_error_message = $errors["{$field_name}][0][value"]->__toString();
     $this->assertEquals($expected_error_message->__toString(), $actual_error_message);
-    // Verify the format value is in the "YYYY-MM-DD HH:MM:SS" format.
-    $this->assertMatchesRegularExpression('/^(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})$/', $arguments['%format']);
   }
 
   /**
diff --git a/core/phpstan-baseline.neon b/core/phpstan-baseline.neon
index a3b1a56779..7920222b19 100644
--- a/core/phpstan-baseline.neon
+++ b/core/phpstan-baseline.neon
@@ -957,7 +957,7 @@ parameters:
 
 		-
 			message: "#^Call to deprecated constant REQUEST_TIME\\: Deprecated in drupal\\:8\\.3\\.0 and is removed from drupal\\:11\\.0\\.0\\. Use \\\\Drupal\\:\\:time\\(\\)\\-\\>getRequestTime\\(\\); $#"
-			count: 5
+			count: 3
 			path: modules/content_translation/src/ContentTranslationHandler.php
 
 		-