In Native advertising, a common use case is to have an endless feed rendering the ads. For example see here https://www.usatoday.com/story/news/nation/2024/03/05/clinton-township-michigan-fire-explosion/72848495007/ and scroll to the bottom of the article, you'll see an endless Taboola feed.
Since we need to auction between any ad that is returned in the contextual flow and the Protected Audiences flow, we will:

1. Have a lot of calls to the Trusted Server, carrying high network and server costs.
2. Slow the ad rendering since each ad slot auction is done separately, one after the other, to prevent duplications. This impacts on both our business performance and the publisher's page performance.

A solution for this is to have the Protected Audiences flow return X (as an input to the auction) items with their relevant score so we'll know what to position where.

I'll appreciate your thoughts on this.