I tried building out your example and the one thing I noticed that might be causing this issue is that your relative path is /user/{id}, which means that to reach this URL Rewrite endpoint you’d have to type in xxx.xx/user/user/234. When you’re entering in xxx.xx/user/234, you’re not completing the relative path so it’s following the standard /users/234 routing.
If my assessment here is correct, you’ll notice that http://localhost:8080/user/user/234 will trigger the URL Rewrite (though you may find the wrong parameter value is passed with the addition of another path component)