When the final descent was commenced, there was a lot of abnormal oscillation in pitch and roll. May be some problems have developed in the IMU or the propulsion system ?
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This is how the forward/backward speed changed with elevator input in the normal part of the flight ( in P mode ) :
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Near the end of the flight, the forward/backward speed changed in the right direction but there seems to be some significant delay :
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Let's look at the alieron control which the OP complained about. This is how the lateral speed changed with aileron input in the normal part of the flight. There was an instance where the lateral speed changed without aileron input. May be the craft was correcting it's position.
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When "things went crazy", the craft did move sideway by itself, likely due to chasing after erroneous GPS fixes but it also responded to aileron input but again, the response seems to be significantly delayed. The failure to halt the unexpected movement of the craft was also partly due to the OP releasing the aileron stick momentarily.
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It appears to me that the delayed response of the craft to control input is part of the causes of the crash. May be some fault has developed as indicated by the abnormal oscillation in pitch and roll.