Существует ли псевдоним для ссылок на пользователей u/username, который можно использовать для ссылки на конкретную страницу их профиля?

[merefield (Robert)]

Кстати, это документировано здесь:

Creating quick access links to Discourse preference pages

This guide explains how to create easy-to-use links that direct users to specific sections of their Discourse preferences. These links work for any user on your Discourse instance. Required user level: All users Navigating to specific sections of user preferences in Discourse can be made easier with relative links. These links are universal and will work for any user on your Discourse instance. Here’s how to create and use these handy links. Creating relati…