Yeah, Lindsay over on Twitter is saying that a lot of it has to do with screen time and salary, frustration over being underused, and wanting to look for better opportunities closer to home, instead of flying all the way to Vancouver to film a couple of 1-minute scenes.
https://twitter.com/lemon_buzz
Flo asked to be downgraded to a recurring character, and the show agreed. My guess is that she'll be in 10-12 episodes next season, but how much time in each remains to be seen.
IMO, the show has really fumbled the ball on this. They should done everything to keep her on as a regular and upped her screen time.