I need help: FlyAway from 3 waypoint simple mission

Hello everyone, my name is Fabio and I’m a beginner.
My exa, Firmware Version V3.1.2, flown away from simple 3 waypoint mission.
Reached the waypoint 1, goes correctly to the Wp2 (telemetry time 2600) , but after a short (telemetry time 2740) loses the route, and accelerates to full speed in the wrong direction.
On telemetry, I see that at the point where it starts to go wrong, the parameter DAcx has a sudden change. I can not understand why …

Time2600: Waypoint reached: it directs to the next
Time2740: unexplained acceleration: fly away

Thanks in advance

That Bad GPS might be the problem. Try to put GPS higher using a pedestal, away from other electronics like ESC.