As seen in the bug report, this setting is a bit confusing. First, it
refers to "message activity" but in reality it does take into account
all events. This is fine in my opinion, so I clarified that point.
Another thing is that it wasn't clear that timeline visibility settings
currently affect the sorting, so I added a tip about that.
Finally I wasn't happy with these two options being called "Activity"
so the old "Activity" setting is now called "Importance". The "Last
Message Activity" setting is now called "Newest Events".
BUG: 508480
FIXED-IN: 25.12.0
24d4829ba9