There is no any issue here, all is correct. This is a thread icon, you can see all kind of thread icons in the forum footer area, there are descriptions for them.

Okay, so it would be better not to use the avatar of the person who started the discussion.
Abatar + icon creates chaos in my opinion.

Hi @ricsca,

Please note that there are 5 forum layouts for such cases, If you think some of the layout is not fit your needs, you can consider others. There is no "it would be better" phrase for a forum software that is used by dozens of thousands users, because it'll always be better only for a certain group of people, that's why we provide more than one forum layout. Each one is created for certain use cases. 

The extended layout is not a "avatar-rich" layout, as you can see it's designed to provide more information about the thread content and status. People use this layout even with avatars (they disable avatars), so you don't see any avatars in the post list as well.

This is the original view of Extended Layout topic list: