Hi @jamesosborne
I Have contacted at Adsense help center for dropped revenue. So they replied-
“`In your case, I found that there is no discoverable non-amp pages for your website.
As per my experience you should keep live non-amp pages also along with amp pages.
And define canonical in both types of pages.
This means set non-amp page as canonical for amp pages and vice versa.
However it is not an error, but you can see the drop in revenue, I think it is because of lack of non-amp pages.`”
But we are at Standard mode of AMP and here is non-amp version is not available. So kindly clarify about it please.
Thanks