I won't consider this as bug.
Rather i should say you have misunderstood the feature.
The search bar provides feature of searching topic which exist in hede.io .
But you searched by a username.
Hede caught it as a topic and as there is no topic regarding your searched text, it showed an empty page (not an error)
Here you can see a working screenshot below-
Here you can see typing some words automatically showing suggestion with matching topic.
Join utopian's discord server where you can discuss these matters with other bug-hunter . To join click here
But soon a mod will leave a reply.
I am not an official of @utopian-io
Yeah, it makes sense too .. It should not give "on behalf of user" suggestions, except for "top articles / topic" suggestions. it is better and does not make user confused, Thank you .. at least hede.io have little suggestion from my report @sourovafrin