The PAAPI component auctions may be a unique place for the browser to inject some very useful metadata.

One way in which fraudulent sites with stolen or nonsense content (eg https://web.archive.org/web/20150215194109/http://cookthefood.com/baking-of-naan-bread-for-good-flavor/ ) remain profitable is via the audience data of the users that go there, often via non-user-initiated navigation. For example, a pop-under network ( eg the one described at https://www.theregister.com/2022/12/22/google_ad_popunder_scam/ ) may send non-user initiated traffic to an MFA (made for advertising) site, yet third party cookies with user interest group data makes the advertising on these nonsense sites profitable.

Getting rid of third party cookies held the very real promise of removing these drains on advertising budgets and publisher revenue from the internet. However, sandbox proposals may keep them on life support.

If PAAPI exposes to all component sellers if the navigation were user-initiated or not, or perhaps a more reliable referral source than the one reported by the fraudulent publisher, it may help solve one of the more fundamental problems in open market internet advertising; eliminating one particular dark hole of advertising budgets.