Track/untrack (follow/unfollow) a room
Currently the Matrix specification only allows to choose whether to trigger notifications or not for a room. Some people (like me) also like to not be aware of activity in some rooms (the room being bold in the room list in Fractal), but still receive notifications for mentions.
I am not sure of the wording, whether "track" or "follow" (or something else) is clearer for this feature.
This would imply contributing the feature to the Matrix specification as well.
Other implementations
Element Web tracks the activity of a room as long as it has at least mentions notifications but does not if it is muted.
Discourse has 4 settings for notifications: