Warp Scale Factor should default to 1
The Warp By Vector and Warp By Scalar filters each has an option named Scale Factor that scales the displacement by a multiplier. The initial value in the properties panel is set to some odd value based on the bounds of the data and scale of the displacement field (I guess). This makes absolutely no sense.
Displacement vectors are almost always defined in spatial units. Thus, the only default that makes sense is 1.