It's fake. Similar items have been making appearance for over a year. People just copy the item description into text editor, change a few things and copy it back into chat.

Yup, there are all sorts of ways to fake item links if you take some time to experiment and decode the text. You can mark contraband as unbound, set equipment as stolen, change its motif, all sorts of stuff. UESP has some datamined item lists, though I'm not sure how recent those lists are.

None of it is actually useful for anything except showing off to or fooling your friends, and as long as you stay sharp there's no reason why it should cause you any grief (for example, carefully examine an item in mail before buying it CoD, even if the linked item claimed it was one thing, you could actually be getting something else).

Well, one way to tell is to remember that after V1, potions are at the 5s. V5, V10, and V15. If they were going to release another one, it would not be until V20.