The reason you need to wrap static ads from your original setup with Ezoic code is so they can be recognized by our system on Ezoic versions for ad density purposes and so that these ads are included in testing and reporting.
Wrapping the ads essentially turns them into a placeholder (a potential location where ads could show depending upon information gathered by the A.I about user behavior) on Ezoic Ad Tester versions of the site.
Some original ads like Adsense auto ads scripts will be automatically removed on Ezoic versions by the Ezoic system.
Here's a video and guide on how to wrap your existing ads:
https://support.ezoic.com/en/support/solutions/articles/48000453920-how-to-wrap-ads-for-ad-tester-video
https://support.ezoic.com/kb/article/how-to-wrap-your-ads