So in a few seconds he used his Force powers to dye his hair?
I think that’s just due to the fact that it was overcast while filming the TFA scene, but sunny while filming the TLJ scene.
So in a few seconds he used his Force powers to change the weather?
Probably for comedic effect.
I mean, if you need to come up with an in-universe explanation for a very minor issue brought on by the realities of production, then sure.