If you have weird behavior on the custom-made header in Divi Builder, when you load i.e. the WooCommerce Shop page, then you have to consider removing the Divi Custom Post Types Default CSS that is style-cpt.css.
So check the page with the link below to get rid of that and restore your header or other parts of the page.
Source: https://gist.github.com/felixhirschfeld/ebf77eeaae71d8834cbe8e635c2a0966
/**
* Disable Divi CPT CSS
**/
function disable_cptdivi() {
remove_action( 'wp_enqueue_scripts', 'et_divi_replace_stylesheet', 99999998 );
}
add_action('init', 'disable_cptdivi');
You can also read this useful explanation with a working also code: https://www.mrkwp.com/2018/08/divi-custom-post-types-default-css/