See https://www.woltlab.com/community/thread/294551-fehlende-benutzer-online-markierung-in-erw%C3%A4hnungen/
{* user no longer exists, use plain output rather than using a broken link *}
@{$username}{* no newline after the tag
*}{else}
- <a href="{link controller='User' object=$userProfile->getDecoratedObject()}{/link}" class="userMention userLink" data-object-id="{@$userProfile->userID}">{$userProfile->username}</a>{* no newline after the tag
+ <a href="{link controller='User' object=$userProfile->getDecoratedObject()}{/link}" class="userMention userLink" data-object-id="{@$userProfile->userID}">{@$userProfile->getFormattedUsername()}</a>{* no newline after the tag
*}{/if}