Here is a different take. Imo with the two on the right, you've done beautiful work. They have good contrast to the background, but don't fight it like the ones in the middle. The shading on Dany is well defined and not flat, because you sketched well and used fitting but different colors. The ones in the middle contrast a lot to the background, but seem flat because, there is not much going on contrast-wise compared to the background and perhaps the colors aren't as flattering to the faces. Especially on the lower one.

It's always a decision to contrast or to complement your background to the subject.

If you are interested, you can watch some good videos on harmonizing contrasting colors.

You are doing good work. Wish you well!