She said it multiple times, especially during the NYCC at all the interview tables she did, basically. I think she even mentioned it during the panel. There’s also quite a few articles out there saying how it’s the last time for her.
I just don’t take that too seriously for now. I think it’ll depends on the rating of this season, and if they’re as good as season 10’s, I’m sure Fox will find a way to convince her (💰) if she hasn’t already signed for season 12. We’ll see…