I know where the prophecy is from - I just see no reason to interpret this as fake when high elves like Glorfindel are already canonically known to have the gift of sight and the prophecy was fulfilled. Given the Macbeth connection, without evidence from Tolkien there really isn’t any good reason to assume the prophecy was fake.
It was a prophecy from Glorfindel, He will not return to this land. Far off yet is his doom, and not by the hand of man will he fall. , which isn’t much but the nazgul were aware of it. https://scifi.stackexchange.com/questions/59204/in-the-lord-of-the-rings-was-the-witch-king-aware-of-the-prophecy-about-his-dea
That can be viewed as a real prophecy or a fake self fulfilling prophecy.
I know where the prophecy is from - I just see no reason to interpret this as fake when high elves like Glorfindel are already canonically known to have the gift of sight and the prophecy was fulfilled. Given the Macbeth connection, without evidence from Tolkien there really isn’t any good reason to assume the prophecy was fake.