Deactivated Members Removed From Past Calendar Attendance

I have noticed that on any past calendar event, any member who has left or aged out and we deactivated from TroopTrack, no longer show up as having attended that event. We found this because we recently looked back to see who came to an event a few years ago and we did not have a full list because of the deactivated members.

Is this on purpose or is this a bug? Is there a way that deactivated members could still show up on previous events, kinda frozen in time sort of thing? Yes, they are no longer members but they did attend that event and removing them when deactivated screws up the record keeping.