I will leave it idle cellular data off in when I wake up and no I dont have bluetooth on. Extra: this might be a new problem :/
EDIT: It didn't switch to cellular I didnt read the entire reply, I'll try to get up with support if I can, it will be hard for them to fix coz mine was a refurbished and there's no more units in the US (I live in the US) I dont know if it's the app or the drone. Last I contacted them (2 times) they have the same answer which is use a different phone. Thanks for the solution. If got any more researches, ask me.
EDIT #2: I tried it, it didnt either, still doing it even with mobile data off. I could try to get up with support if I can.