Kt, a lot of have experienced being moved from one group to another, sometimes several times and several groups. And usually to our disadvantage. Seems to be a bug or glitch, nothing to do with hacking or cheating. That isn’t to say there are no cheaters or people taking advantage of certain “features”, exploiting the program. That has been confirmed and reported to Rovio.
Edit: I have two players in my group duking it out in 1st and 2nd place. 1st already has 354 stars and 2nd has 305. I am a measly 3rd with 214, but not playing much right now. Blues is already at level 9 anyway.