I think the main thing that took her OOC was the eyes looking so menacing, almost sephiroth vibes, which is :puke:.
I think that's actually mostly because of the perspective changes. The whole thing is about this one event from the perspective of all the different characters, and that's how Tifa views Aerith in the moment. If you look at Aerith during all her own perspective scenes, she's smiling and never looks menacing, once.
I won't argue that Tifa viewing her that way isn't OOC in some way too, but I think that's part of the mission statement, hence why it's a "five point perspective".