Yeah, the (vague) takeaway I get is that AdSense is a small part of their income, with majority coming from direct brand deals.
Since it all comes out of the same marketing budgets eventually, does this mean integrated influencer advertising is meaningfully undercutting digital ads run by the platforms?
Not meaningfully no - most influencer campaigns have a part for ads to support the content so I think in the Balance it probably builds more ad business.
Your earnings vary a lot based on what kind of video you make so it's somewhat complex.