Hello,
The number of DOM elements are generated in the process of content building. All WPBakery/Elementor page builder elements are DOM elements. If you want to reduce DOM elements you will have to reduce the content: widgets, products, menu items, and others.
Also, please provide access to the admin panel and confirm the permission for plugins deactivation, and switching to the parent/default theme. As soon as we complete the testing we will enable all back. Additionally, disable the server cache for proper testing of the website.
Kind Regards