Data loss in SharePoint user profile

I've just discovered that one of the properties in our SharePoint user profiles that we use to record the areas of work for staff has had a mass data loss across all 200 user profiles. I know this is a bit of a shot in the dark but would anyone have an idea why that data loss would happen to only one property?

I'm also exploring whether we have a backup of the data but I imagine that unless one was created that it isn't done automatically by SharePoint or O365?

Thanks!