In certain situations, a constrained object can rapidly roll about its aim vector. Rolling effects can happen when the aim vector approaches or points in the same direction or in the opposite direction as the up vector. For more information, see Rolling effects.
You can avoid rolling effects by keeping the target vector clear of the world up vector’s direction. For example, if the world up vector points in the direction of the scene’s world space Y-axis (the default), you would try to avoid having the positive or negative Y-axis point in the same direction as the target vector. You could move the target object(s) as needed, or perhaps change the target object weights so that the target vector does not get to close to the Y-axis.
However, if your animation makes such avoidances impossible, you can prevent rolling by changing or animating the world up vector. To change the world up vector for normal constraints with the Attribute Editor or Channel Box, edit the World Up Vector attribute/channel as described in Edit normal constraints.
To animate the world up vector for normal constraints with the Channel Box