I think - based on my own experience - you’re probably right when you mentioned maybe you weren’t close enough to this person at first to notice her manipulations. They’re not always easy to spot, anyway.
I’m not saying my ex best friend was manipulative, but... she was kind of self centred, and I just never truly saw it until after she ghosted me during lockdown, when our mutual friend (by then also not friends with my ex friend/her mum) filled me in on a lot of things I hadn’t known about or realised, myself. I did consider us to be close, actually, until lockdown, though I had started feeling uncomfortable around her before the last time I saw her.

I think once people get to a certain point in life, most of them don’t change drastically unless they want to, or something out of their control happens to make them change in some way. Certainly, none of the people I’ve bumped into from high school seemed any different.