Originally Posted by
Halivel
Took a bit longer than it should have because I accidentally skipped the very cutscene I was interested in, so I had to redo it again. Oh well.
I entered the cutscene at around 16.00 Eorzean Time, Fair Sky weather. Not really a sunset yet, but I figured that we'll at least find out if the cutscene has scripted time or not. And as it started, it was dark night, so it does look like the time along with the weather for this cut-scene are locked in. This checks out with the video from YT you've linked, which also has the cutscene happen during dark night with clear skies.
This explains why it looked so dark for you - devs most likely only adjust lightning for specific time and weather when cut scenes have a scripted environment, as there's realistically no need to do the adjustments for an environment that normally shouldn't be seen.
What it doesn't explain is why exactly the script bugged out on you, and why it didn't on me - NG+, by all means, is identical to MSQ in all things but rewards, so theoretically we should be as close to the same entering point as possible.