That Darth Andeddu is implied to have been part of the Sith Empire seen in Tales of the Jedi: The Golden Age of the Sith in spite of the fact that between being a Darth and fleeing to a Deep Core planet, Andeddu doesn’t fit the lore of the Sith Empire. It would have made more sense for Andeddu to be from the New Sith Wars.

That the Dark Jedi ancestors of Naga Sadow were retconned from having lived ~25,000 BBY to having lived ~7000 BBY without any reason being given for the retcon and therefore the conflict between the Jedi and the Dark Jedi ancestors of Naga Sadow was retconned from being the “First Great Schism” to being the “Second Great Schism” in spite of the fact that Tales of the Jedi: The Golden Age of the Sith refers to that conflict as the “First Great Schism”.