In the 2.3 preliminary patch notes, the name of the boss of turn 9 is listed in the New Achievements section. For those who know a bit about Eorzea's lore but haven't reached turn 9 themselves and seen the cutscenes and have been trying to avoid spoilers for it, it could be a very unwanted surprise to have that revealed.
I know I avoided all spoilers and had a simply "OMG" moment when I reached t9 and I don't want the ruined for anyone.