Quadrotor sudden climb, local_ position_ Z drops abnormally

Our UAV first hovered for a while, then suddenly lifted, and finally hung on the protective net. Then we pressed the kill button.
The following is our log analysis: Flight Review - Quadrotor (px4.io)

The position sensor is optical flow(PMW3901).
The distance sensor is tfmini.
Flight control is hollybro pixhawk V4
Here’s a picture of the plane