Estimator fail and following the wrong command

Dear px4 developers, I have found an issue while I was flight testing on my craft. I am using Visual odometry data for the position control. The problem is that I was giving pitch command just a little to move forward, however, it did not respond so well for few seconds, and suddenly it made a strong pitch command which could have been dangerous (it happened in the past something similar, crashing the drone). And then I checked the logs. It shows that before the sudden pitch, the Y velocity is increasing meanwhile there is no movement in Y direction. And then, also there is increasing divergence in Y position. (I have observed that my Visual odometry data is the same as truth). And then it gets into Altitude mode, and at that instance, the high pitch command is triggered. Is there any reason that this is caused? And what would have caused this failutre in the estimator?

Hi, can you share the log?