LO 4 weeks rejecting baby cot

Baby is turning 4 weeks soon! ❤️ However from few days ago bb refused to sleep in cot during night time, whenever we put down she will wake up in 5-10 mins. But when she sleep with us in bed she sleep so soundly but we didnt want to risk it by letting her keep sleeping on our bed. Any idea for this issue mummies? In the day sometimes she ok to sleep in cot sometimes she is not