I finished my package design in adobe illustrator cc, then saved it as a print ready PDF (Press quality), and delivered to the client for print. But he returned back saying that he has a problem with the transparency of the stars(you can see it on image attached)

[![enter image description here](https://i.stack.imgur.com/MdcnR.png)](https://i.stack.imgur.com/MdcnR.png) 

I did read that the transparency cause problems in printing process according to this article (<https://www.selectgp.com/page/file-transparency>) , they say something about flattening, but I don't really know what should I do to overcome this problem!

This image is after flattening the stars as per suggested solution![![enter image description here](https://i.stack.imgur.com/0LbsK.png)][1](https://i.stack.imgur.com/0LbsK.png)