@Yatsuki go read the novel. The change of skin colour is on purpose and important for her character development, due to how she perceives the behaviour of those around her. By not changing her skin colour the manga will become way more shallow and superficial than the novel, the opposite of what you claim.
@HobisFlower it doesn't make the same point at all. It can't possibly make the same point without coming off as exaggerated, forced, half-arsed.
The skin colour change doesn't just happen and then get forgotten about in the novel, it's a major part of her thoughts and how other people interact with her from this point forward. It's supposed to help bring about the culmination of all the racism / prejudice commentary that's been building through the whole story, but that can't happen in the manga now. Now the manga will have to force all of her insecurities and identity crisis on "I can use light magic now" instead of "I'm treated like a human now I don't look different" which will make the 180 change in attitudes of those around her seem way too exaggerated and fake. Or it will have to erase said insecurities and identity crisis, drastically cutting back the development of her character.
No spoilers, but it'll also mean some very important scenes with other characters need to be completely re-assessed, as there's no longer much impact of "they already didn't judge me" vs. the change in behaviour of others just due to
her looks the healing magic. The story is objectively weaker and more shallow now.
Not to mention it was already published with the change in skin colour and then they went back to rewrite history. There's no good justification for this, the only reason could be trying to sweep an uncomfortable look at the reality of racism and prejudice under the carpet.