Also I guess that it's down to whatever Norton decides to classify as trackers and alarm you with that information. I don't know how it classifies them but see this from Ccleaner. It explains in layman's terms what they classify as trackers.

Why are there so many "trackers" found in Health Check? Should I be worried?

If you ask me it's designed to scare the user and make them feel safer in thinking that they have deleted/ removed everything.