A serious problem with Horizon topic cards: in the private messages list, there’s now no longer a way to see who’s in each PM topic, especially if I’m the person who replied last in the topic.
It just shows the PM title, and “dfabulich replied on [date]” and nothing else, especially not who else is in the thread.
I was skeptical of removing the avatar list on the public topics list, but the list of participants is what defines a PM topic, especially since they don’t reside in any “category.” The avatar list should be restored at least for PMs.