Recently, they are pushing most of the ads to their ad servers. It's kind of obvious that they are not following the 70/30 rule.
I think when an ad break comes, they forward the viewer's device to either the Roku ad server or your ad server. and believe me, they have lots of ads (mostly in a pool of 4) waiting to make money for them!
I'm monitoring my ad server traffic, and believe me, compare to a few months ago, the traffic routed to my server is almost one-third of May or April. (and my channel and view hours are growing)