Prior to BFA, she had to deal with the Desolate Council and the meeting between the Forsaken and Humans. That did not turn out how it was supposed to go. Sylvanas wanted the Forsaken to be rejected and not all of them were. She killed them.
I’m not sure if it’s ever discussed what the Forsaken thought about the disappearance of the Desolate Council. They could have been lied to, but she was controlling them pretty heavily. And then they lost their home.
She was losing it I think.