diff --git a/core/config/schema/core.entity.schema.yml b/core/config/schema/core.entity.schema.yml
index df2a2fd..bc192ed 100644
--- a/core/config/schema/core.entity.schema.yml
+++ b/core/config/schema/core.entity.schema.yml
@@ -330,10 +330,10 @@ field.formatter.settings.timestamp_ago:
   label: 'Timestamp ago display format settings'
   mapping:
     future_format:
-      type: string
+      type: text
       label: 'Future format'
     past_format:
-      type: string
+      type: text
       label: 'Past format'
     granularity:
       type: integer
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/TimestampAgoFormatter.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/TimestampAgoFormatter.php
index 55a2fb1..c846552 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/TimestampAgoFormatter.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/TimestampAgoFormatter.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\Core\Field\Plugin\Field\FieldFormatter;
 
-use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Datetime\DateFormatterInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
@@ -187,13 +187,13 @@ protected function formatTimestamp($timestamp) {
     if ($this->request->server->get('REQUEST_TIME') > $timestamp) {
       $result = $this->dateFormatter->formatTimeDiffSince($timestamp, $options);
       $build = [
-        '#markup' => SafeMarkup::format($this->getSetting('past_format'), ['@interval' => $result->getString()]),
+        '#markup' => new FormattableMarkup($this->getSetting('past_format'), ['@interval' => $result->getString()]),
       ];
     }
     else {
       $result = $this->dateFormatter->formatTimeDiffUntil($timestamp, $options);
       $build = [
-        '#markup' => SafeMarkup::format($this->getSetting('future_format'), ['@interval' => $result->getString()]),
+        '#markup' => new FormattableMarkup($this->getSetting('future_format'), ['@interval' => $result->getString()]),
       ];
     }
     CacheableMetadata::createFromObject($result)->applyTo($build);