We as humans determine the characteristics of any type of body, mass or 'massless', from our frame of reference. However, if we were to change our frame of reference with respect to velocity and then take measurements from that frame would we see the speed of light increase. So for instance say we are traveling in that long debated car at 50% of what we use to perceive as the speed of light on Earth but now we have measured as 500% greater in the direction we're traveling.
Observation point A) Earth reference point parallel to beam of light the speed of which is 1x; Observation point B) Traveling 50% of observed point A speed of light now observed to be 5x so traveling at 1/10th the speed of light at observed point B.
This anomaly would only be detectable if we were traveling in the direction of the beam of light because that would be the frame of reference that would be significant to the study. Measuring light from a perpendicular stationary frame of reference while traveling at 50% the velocity of light of Earth observation point A would result in the same findings. I suggest the velocity of light is relative to each observation point and frame of reference and that light itself is subject to time dilation which is the difference observation points.