This is how my mimd works, so bear with me. Ran across an intense video from the Veritasium channel, which I'll post later. He poses a truly amazing question: how fast is the ONE-WAY speed of light?
We know for a fact that the ROUND TRIP speed of light is c because we can bounce a laser off a reflector on the moon and measure it. But we have no way at present to observe and measure the one way speed of light. It could be that light travels faster in one direction than in another after all, but we can't prove it one way or the other.
So the round trip speed of light is a fact, whereas the one way speed of light is a theory. Granted, its probably a good solid theory, but remains unproven. Eh, will do opinion later. Its bedtime.