diff -u b/core/modules/user/user.api.php b/core/modules/user/user.api.php
--- b/core/modules/user/user.api.php
+++ b/core/modules/user/user.api.php
@@ -116,6 +116,7 @@
  *   If $name has trusted HTML content, a MarkupInterface object should be used.
  * @param \Drupal\Core\Session\AccountInterface $account
  *   The user object on which the operation is being performed.
+ *   The account object passed to user_format_name().
  *
  * @see \Drupal\Core\Session\AccountInterface::getDisplayName()
  */