Preload does not suffer the same issue as pinning using a header. All sites on the list would just look like you probably visited them, which means ambiguity.

Preload does not suffer the same issue as pinning using a header. All sites on the list would just look like you probably visited them, which means ambiguity. Not all UAs share the same preload list, but they all borrow from the chrome preload list. Read here https://hstspreload.appspot.com/ https://hstspreload.appspot.com/. Its not a great ecosystem and I dont forsee it as one that is improving, with encryption being a big issue in some countries