Copter 4.3.4 crashed while gaining altitude

Our UAV which uses Pixhawk Orange has 4 T-Motor MN 4014 brushless motors. There is Drone, Ground-Station and Rc Controller. First of all we got all the calibrations (ESC, GPS, COMPASS). We Flew around 15 minutes. The Drone had 2 Ultrasonic sensors which handle the pitch. During flight, there were some deflections on the pitch because of the Ultrasonic sensors’s bad quality. However, when it came to last flight, we removed the Ultrasonic sensors. After that when we started to our last flight; we pulled up the throttle. While it’s gaining, as you can see in the logs, the motor-4 stayed lower than 3 motors as pwm value. Then, the drone flipped to the it’s back. We couldn’t understand that’s why. After it flipped to it’s back, we cut the throttle but it was in the irreversible situatuon (while cutting the throttle, I got panic and got down the pitch also).

The Video of crash= 04/03/2023 Eagle Tech UAV Crash - YouTube

Logs =
Logs As Bin Doc=