Grabbed this quote from the other thread, but figured I would go ahead and point out that this was essentially click bait. The speed of light is known to not be "constant" in all scenarios. Without getting too technical it's actually a reason why lenses and fiber optics works. The speed of light varies in different medium. That should have been reflected more in the article titles. They aren't arguing about if the max speed of light is constant. They are investigating the permittivity of free space or the "vacuum of space" and how it affects our measured constant.
BTW the deer thing is extremely creepy for some reason...