I can’t believe this hasn’t already been discussed, but if it has, I couldn’t find it. My apologies if this is a duplicate.
“Suggested topics” shows unread topics until there are no more of those and then displays new topics.
It will display first new topics in the categories I’m watching.
Here on Meta, it invariably displays support topics first, which is not a category I’m watching.
I imagine I would not be the only person to find it helpful if new topics from watched categories were displayed first.