Thank you for replying. I appreciate it.

I don't know, it looks like on Dec 11th this problem disappeared. Ad requests for pubads.g.doubleclick.net. went from 12,000 a day to under 100, then in January there has been a slight increase to between 500 to1000 ad requests per day.

The thing is that almost 70%-80% of my Daily Adsense impressions (over 300,000 ad requests/day) are served through DFP when Adsense is allowed to compete against my Line Items, so pubads.g.doubleclick.net in my sites report can't be referring to those requests.

Also, the numbers don't line up with the one Ad Network where I use Adsense as a default

I've made so many changes with Ad networks and their defaults that it's impossible for me to go back and figure out what happened on December 15th and January 1st. 

Do you happen to know if this could be an reporting issue with Adsense, Maybe changes were made internally on those dates?

Thanks