In the real life, the sun only appears orange, because of the way that our atmosphere affects the suns rays. These rays which are normally perceived as white light, split up into different colors. That's why when you see the sun at certain times, it is red, orange, and variations of yellow.

However, in actuality, if you were to go onto the moon, or anywhere in space, you would find that the sun is actually ALL colors, and not just one. This causes the sun to be WHITE to the naked eye. Of course, you couldn't just stare at it without ample protection, but it is still not yellow, red, or orange, contrary to what we are taught as kids. It's an extremely common misconception on earth. You see the misconception displayed in a lot of video games; including space epics such as Warframe. (The devs of that game couldn't even get the color of OUR sun right.)

So my question is.. why is the sun orange/yellowish in the trailers for Endwalker. I know the sun isn't literally the same as earth, but if it is supposed to be based around the same type of sun we have, then white might perhaps be a better color. Is this a dev oversight? Or might the sources sun have something to it that we do not know about, hence making the color that we see from the moon.

If you don't believe me, look at these sources. The sun is NOT what you think of it as. Most pictures used in education are in infrared, and are not actually the true appearance of the sun.

https://en.wikipedia.org/wiki/Sun
https://www.youtube.com/watch?v=6fl1JXesYhc
http://solar-center.stanford.edu/SID.../GreenSun.html