When you use a username link (like https://discuss.flarum.org/u/2006bt) to visit the homepage of a user,if his username is purely numeric,Flarum will think you are requesting a UID.
The most typical example is @010101(https://discuss.flarum.org/u/010101).
When hovering the mouse over the avatar, there is no problem with information such as Bio

But when you visit his homepage, Flarum will return another user's information(UID 10101,@dkio).
