Plane doesn't follow mission waypoints in Auto mode and changes flight modes on its own

Hello! I am new here and I don’t have much experience.
we are preparing for a competition and we need auto flight.
We have a pixhawk cube orange and here 3 GNSS. Version 4.2
We don’t have an airpeed sensor and lidar.

We are having problems with auto modes. The plane doesn’t follow waypoints! and in the last flight when it got out of waypoint I switched to FBWA mode and begin landing. When it got near ground it gave full throttle on its own and started to go up again. I look at pc and I saw it was at RTL mode. But in my transmitter and mission planer I have only Auto and FBWA modes designated. I took it to FBWA again on mission planner and got the control but suddenly the same thing happened.
I am not sure what to upload here but I put some files.

flight route and waypoints


Your plane has not received any PID tuning yet.
You should follow the instructions here .

Next your plane switches to RTL according to your parameter settings:
GCS Failsafe On

Hope this helps.

Yep, it will change to RTL mode when failsafe is detect ie loss of signal from gcs or transmitter.
U need to find out whats up with your rc range, if it didn’t go to rtl you would have crashed