On the feature detail page, it is possible to toggle "Suspend active development" in the UI using the "..." menu on the overview section. When this is toggled, there is no visible indication that it is turned on. This setting will hide features from the roadmap page, and will prevent the milestones Gantt chart from displaying, so it should be more clear to the user that this setting has been toggled on.
Perhaps adding another banner will be indicative enough?