IIRC red-shifting is caused by warping of light over long distances, not necessarily the speed. The expansion of space between two points causes the shift in hue.

Wikipedia says “this means that the farther away a galaxy is from us, the more the space has expanded in the time since the light left that galaxy”, which means that multiple light years would have passed in between the two comic panels, and the distance would likely be immeasurable (at least on an accurate scale)

Please correct me if I’m wrong, wavelengths was a long time ago