Really like green background. But ok I can see this is probably not the result you wanted. ..but learned placing AI on top of one another most often results in the bottom color disolving and mixing with top with a darkness added to the new color.
I see where you were going with this. The green background is really great. And I think you could salvage this piece by adding white pen from the week 2 challenges. Which would lighten up the red. And maybe cut the image out.