This is configured under anomaly settings. You can change the threshold or just disable the problems based on that under "applications." You can also edit the individual application specific anomaly detection settings to change it for individual applications:
Dynatrace is learning patterns of such things like traffic. So in such case when there is violation of this metric it can be raised as a problem. It is possible thet there was traffic drop from short amount of time but it fulfilled incident and problem has been fired.