All deployed DataPages impact data transfer. SEO deployment enables search engines to find and index your database content and drive traffic to your web app. When a search engine bot downloads your pages for indexing, data transfer is incurred. This could potentially result in higher data transfer when your pages are initially indexed and later when the data changes.
You can monitor your monthly data transfer usage in the billing section of your account. If you observe a spike in your data transfer usage and you want to know the impact of SEO deployed DataPage, you can look into your server logs or ask your webmaster to perform logs analysis to determine where the traffic is coming from.