I had a look in the Divi implementation. For this comments, Divi is not using any specific function/event. It is completely hardcoded as CSS comment in the following files (details below). My plugin is removing the generator tag of Divi; However I would not recommend modifying the core Divi CSS files programmatically because that might cause problems in future updates of Divi (as Divi keeps changing its implementation quite frequently). If you still want to remove these comments, I would suggest to manually remove the comment entries from Divi CSS files.
Inside wp-content\themes
Divi\style-cpt-rtl.min.css
Divi\style-cpt.min.css
Divi\style-rtl.min.css
Divi\style-static-cpt-rtl.min.css
Divi\style-static-cpt.min.css
Divi\style-static-rtl.min.css
Divi\style-static.min.css
Divi\style.css
Divi\style.min.css
These CSS comments are present:
/*!
Theme Name: Divi
Theme URI: https://www.elegantthemes.com/gallery/divi/
Version: 4.15.0
Description: Smart. Flexible. Beautiful. Divi is the most powerful theme in our collection.
Author: Elegant Themes
Author URI: https://www.elegantthemes.com
License: GNU General Public License v2
License URI: https://www.gnu.org/licenses/gpl-2.0.html
*/
Ideally these comment lines should be removed from all CSS files. However when we view source generally (for most websites) style.min.css is used. So if you remove the comment from that file only, then it would disappear from view source. If you need any help from me, please let me know.
Thanks & Regards,
Pankaj