I would not say correct her, I would prefere to explain her, in simply terms, that in case the color have more meaning, as well as moon may be the ball on the sky in one context, while in other context it is just time span of 28-31 days, where the current values came from animosities of rules of some far country many centuries ago (moths named after the rules and MY month cannot be shorter then HIS month).
Somebody would tell here soon anyway, better be it you in nice and friendly environment, then some rude, which does not know better (and just got splinter of that information) say her "you are just wrong and therefore stupid and not white at all, if you are asian" (or somethin more rude).
Going with the month paralel, I would agree, that here skin is nice white (and the ribbon goes relly well to it), but as the word moon have more meanings and some have historical roots, which does not even matter now, the white has also more meening when connected to people, which have some historical roots, when in old times peole realized, that some have white skin, some dark, some more yellow tones or red and came with simplification to call whole nations by colors, they had seen as different in majority, but does not have so much validity now, when anybody can marry anybody and there is many times not strict distinction, what exactly the supposed "color" even should be. Mainly if while her ancestry is from asia, but her skin is a lot whiter, than of some people from say europe. So that she is right that she is white as far as it goes to skin color, but also there is the ancestry, that her family goes from Asia, so she is also Asian.
And that is like if Ted's family came from Austin in Texas, so he is both American and Texasan and Austian at the same time and it is not conflict or problem. And Ava is from family, which have roots in Africa and her skin is darker, but not so dark as skin of (there must be somebody darker than Ava, if not in neiborhood, then on TV she see).
And that she is white (as per skin tone) as Chloe, but that Chloe family came from this state/city there and your from that state/city so there are also small differencies in that. As well as there are differencies in hair color and eye color and that that she prefere different color of robe/ribon, than Chloe does. And that that all those differencies of colors does not matter co much, even if they exist.
(or something like that)
You cannot prevent her from the facts in the world, but you can explain her in the terms, that she would uderstant and be not ashamed when she is confronted with it, rather to be proud. "Yes, I am Asian and I an as white as Chloe, who American and Hans, who is German. Some Americans are not even so white as I am. Why it should matter anyway?"
I am from Europe and at 3 I was aware, that in Africa live black people and that some childs around have different color and different heritage. I did not care much at that time. I owned lot of planets, where lived people and animals of all possible colors in harmony.
I remember, that around 5 I did know some basic about that people are borned, not that they are found under rose or crow brings them or so. My mother was pregnant and I know, that there is my sister inside her, but the sister is just so small baby, that she had to be protected by my mother body all the time and that when she will grow more, she would be able came out and play with me and I would have protect here. (well no technical detail, how it is exactly done, but I do not care, it was natural, that it happens somehow at the right time. I was allowed to touch the tummy, she was inside, feel her to move there and sometimes kick, but I must be gently, to not hurt or scare her. Around my 6 I was allowed to carry my sister part of way home when she was finally born (well probably hard supervised by my parents, but I was the Prince, who have little Princess in his hands and was resposible to walk steady and held her firm oh her first way home). I still remembere, ho I was disapointed, that she does not play with me ans still cry and does not grow at all, even if I checked here like 5x a day)
So maybe it is hard to believe now, when your dauther is just 3, but in two year she may even hear something about how are child born - you cannot pretend to her for long, until she get some hints from other sources. So I think, it is better to be open with her, just on the level she needs to know about world around - simple level, sure and not much details, but not lie to her and do not think, she could not discover something until you explicitly allow her to as it does not work that way.
On the other hand do not push much details and burden on her, answer her questions honestly, but with regards to her age, do not avoid difficult themas, but you need not go in too much deep and force her to know and agree on hard reality.
If you cannot totally shield her from reality, it is better to prepare her gently in loving and safe environment to the parts of reality, which she is going to meet soon, that just deny it all and try to fix results, when damage is done. With carefull approach the damage may be prevented a she can accept it as all other odities of world, she had to accept so far (why is mom so much larger than me? Well she is older so she had longer time to grow. But granny is not larger hat father, even if she is older. Well no everyone grows equally fast and older people does not gro so much ... ok, it make sence now, even if it just small part of really komplext biological science)
So she is white, as well as asian, as well as Princess of ponny kingdom - it is all true now but more important is, that she lives in loving family and is acepted as who is is without questions.
You are caring about her and THAT is important. She have safe and loving home and THAT counts much more than that in the world around are some illogical or unpleasant things.