In RTL mode:my copter re-takeoff before landing

there is some unkown reason that make my copter re-takeoff 1-2 meters before landing phase in RTL mode。
I use a sonar (TF02),and a hereflow。

within analysis the flight bin。

i found that there may some disturbence to the baro alt before landing. and throttle start to compensate for the alt loss

but i use the sonar, if there is some parameters that control the cube to use baroalt or sonar ?

It is recommended to share your bin files.