Awcine

to put it another way, a front anamorphic 100mm lens has a cone of light in image space that is vertically a 100mm image, and horizontally a 50mm image.  Since a 100mm lens has 4x less depth of field as a 50mm, it will defocus at 4x the rate of the horizontal axis, while the image will be desqueezed at a constant 2x, meaning the further you throw something out of focus, the taller it will get.
Conversely, a rear anamorphic 100mm lens has a cone of light in image space that is 100mm vertically and horizontally, and is then squeezed at a constant 2x, so you wouldn’t have the same asymmetric depth of field.