Why my logo "Health Cube Logo" has been rejected?

My logo “Health Cube Logo” has been rejected. I only got information that “it isn’t at the quality standard required to move forward”. Could you give me some advice?

This is a wonderful design.

For starters, your shadow needs to be softer if it is absolutely necessary you have it otherwise, I would suggest you drop it.

You could also do better on the gradient and typography.