See who can be assigned to my topic

When I clic on ASSIGN I get this screen


I don’t understand the criteria to show the people picture.
There are more than these one on the staff/moderator group.
If I use the @ for the name, I get more people


some of them are even not staff member

I need to understand better how this works. ¿Can someone help?

The criteria for that list of suggested users is defined here

It basically boils down to the current user + up to 6 other users who don’t have assignments that exceed the number set in the max_assigned_topics setting.

Can you check the assign_allowed_on_groups site setting on your site? Members of groups added to that setting will show up if you use the search input.