There was also something about mindflayers having no souls, which unless it is a 5e retcon, is a Larian retcon, because Mindflayers definitely had souls back in the day with my 3rd and 2nd edition material.
But yeah, that aspect certainly struck me as a rather drastic departure from prior depictions of mindflayers, particularly because it's an aspect of their biology/culture that Larian changed that is so very critical to the plot of the game.
At least with the many other departures from their prior lore things were handwaved away with the excuse of 'netherese tadpoles'.
