Dont understand Defender Report

"I've finished scanning http://www.ncbaroqueorchestra.org for vulnerabilities and I found 1 issues that you should take a closer look at!

File Issue
CSS.php /home4/ncbaroqu/public_html/wp-content/plugins/child-theme-configurator/includes/classes/CSS.php Suspicious function found"

I have copied the offending file into Word. Which I could upload. It is a very long text file. I checked the files on my testsite (localhost) and the file is there. So, I know where it came from!