this is not flat chest, this is small breasts.

Pulsatrix said:
this is not flat chest, this is small breasts.

And this is a problem....why?

Not a nude filter, just an alternate version from the set.

Well, I don't have this CG set, so I can't verify, but are you certain? This part where her clothes are removed doesn't look like it was from the original artist. Also, this image is not near the same resolution as the parent or the others, so it's hard to believe this is from the original set.

Pulsatrix said:
this is not flat chest, this is small breasts.

For tagging purposes, there is no difference.
However, I wouldn't even say this size is "small".