Hello,
What route do you go inside Adsense to turn these 3rd party ad networks off?
Blocking controls > Content > All sites > Manage Ad Networks
And there, the joy begins, because, since a couple of years, you have to disable each ad network , one by one , and the more are disabled, the slower the page is to refresh ! When I did it, it took me several days to disable the 5000+ ad networks. (I was doing sessions of 30 minutes, because it was so bothering and long).
Now, if you change your mind, guess what, you need to re-enable them one by one too, and here you go for hours/days. #NeverStopTheFun
edit: you'll notice that tens are labelled "do not use", or "outdated", or things like that, so I wonder why t hey are still "active"...
edit 2 : just to say, this is what I did, but, it doesn't mean I recomand it, so do this at your own risk, this certainly has unpredictable impact depending of niches, user profile, etc... this can drastically hurt your ad inventory too.