Due to the way ads in AMP work, a publisher's ad network might see referrers and URLs that are different than the publisher's domain.
This can lead to confusion at times, however it's a byproduct of the how ads in AMP function, which is explained here.
Ads in AMP
All ads in AMP pages are loaded inside an external iframe. It's an official AMP policy that needs to be followed by all publishers who implement AMP, as explained in the official AMP documentation.
A publisher's Marfeel-produced AMP pages are generated by Marfeel and use an iframe for ads hosted under the ampproject.marfeel.com or ampproject-b.marfeel.com domain.
AMP allows publishers to customize the iframe domain. If it's not customized, the domain of the iframe is ampproject.net (or in the case of Marfeel-produced AMP pages - ampproject.marfeel.com or ampproject-b.marfeel.com), however the ad within the AMP pages is always loaded inside an external iframe with a domain that is different than the publisher's domain.
This is the case for all publishers, including those without Marfeel-produced AMP pages.
Information sent to ad networks
Even though the ad is in an external iframe, the AMP runtime sends the proper URL and referrer information of the actual article.
For example, if information from a DFP tag of an AMP page from a Marfeel partner needs to be sent to DFP, all the corresponding information (article URL, referrer, etc.) is sent to DFP. What occasionally leads to the confusion of the publisher's ad network is the URL they might see for the iframe (ampproject.marfeel.com or ampproject-b.marfeel.com...).
This can be observed in the following examples when inspecting both a Marfeel and non-Marfeel publisher's source code with Chrome's DevTools to identify the information being sent to DFP.
Marfeel-produced AMP pages allow publishers to maintain the same configuration from both the mobile web and AMP, however if publishers want a different configuration in their AMP pages than on the mobile web, Marfeel can implement this.
If interested in a different configuration on these channels (mobile web and AMP) please contact your Customer Success Executive.