Throttle increase after certain heigh

Dear All,

I am using Speedybee F4 v3 flight controller with latest firmware
The setup as per the picture, basically no GPS, MTF-01 Optical Flow Sensor attached.



The problem is that when I take off in FlowHold mode, I can only lift the drone up to about 1.6 meters. Beyond that, the drone will suddenly lift up uncontrollably.

I have attached the bin file here.

and video here.

Appreciate your help.