Why FW always tents to increase throttle in land mode?

Here is one of the logs

According to the log, at 19:17 the altitude setpoint is 7m (the ground altitude), I think it turned into land mode. however, at 19:25 the throttle increase to 20%. I cant understand what caused the autopilot decides to increasing throttle in land mode.

I’ll be able to take a closer look at this later this week, but as a start you should try to set FW_LND_ANG (the glide slope angle) to something achievable by your vehicle.

Thanks. I set FW_LND_ANG from 15 to 10, and the throttle seems normal in land mode.
But I still cant find out the reason of increasing throttle when I set a high glide slope angle.