Forums have today 4 templates that should be simplified.
It taste & feels a lot like the forum havent been really updated for a long time.
is the main wrapper that keeps forums, topic & pager inside it, markup is a div wrapper. Thats not needed.
Is the main forum overview.
Contains a div & span that sets the icon for the forum That should be inside forum-list.html.twig where it belongs
Is the by user on date snippet on a forum, should be in the forum-list.html, the seperation here makes little sense, feels like its leftover from wayback.
Looking at these templates it should be merged down to 1-2 files.
forum-submitted.html.twig into forum-list.html.twig and rename the file to be called
get it done