Gigazelle Your answer does not take into account that we are talking about First Time Visits (Visit number = 1, Dimension: Visit).
Regarding the entries metric, original referring domain and referring domain should be equal for first time visits.
I found the solution: it lies in Adobe backend on how they process referrer information.
Since our implementation is done via GTM, it is characterized as "non-javascript" for Adobe. And if referrer value is blank and tracking call is non-javascript, then Adobe ignores this for the referrer report! And the confusion starts here: it does not do so for the original referring domain report!
If later on during the journey a referrer is passed, lets say google, then Adobe counts this as referrer and thus the entry is attributed to the first valid referrer instance, which in this case is google - no matter if is happened later on in the journey.
