It will depend on where you are adding the placeholder on your page. If you are adding it via the chrome extension to the div where your menu is then this will likely be why the menu is getting pushed to the site.
If you have a WordPress site, Have you had a chance to check out our Wordpress plugin for setting up Placeholders automatically?
The plugin will generate Placeholders for you and create an optimal layout across your whole site. This also means they're hardcoded if you'd like to change your theme in the future without impacting your site's revenue performance.
Once you have the plugin installed, go to your WordPress Settings, select Ezoic and then update the Ad Settings to add placeholders. You will want to enable the option to Generate Default Placeholders.
More details are available on this page: https://support.ezoic.com/kb/article/setting-up-ad-tester-placeholders-with-the-ezoic-wordpress-plugin