You cannot do that with a bbcode directly. A bbcode cannot "look up" a user to see what color they should be. All a bbcode does is take your "TEXT" parameter and replace it with the text you type into the post.
If you type into your post, it would replace the TEXT with "Santa Claus". Your bbcode would have no idea whether Santa Claus is a user of your board or not. If you have some special [user] bbcode, then you must have an extension that is enabling the bbcode to do that.
If you type
Code:
[newu]Santa Claus[/newu]Statistics: Posted by Brf — Thu Jan 02, 2025 5:27 pm