I am also curious of the process or the state of the DC archives. Ie: is it a paper stock issue?
I have seen threads (on here probably) showing the golden age superman omnibus vs original comic and the original comic in some cases had more detail so they probably don't always have access to original or high quality second generation copies (or maybe it was an earlier digital clean up process).
In the Flash silver age TP, I recall one page just seeming a bit blurry compared to the previous and next page,