Phia's AI shopping extension reportedly used cookie stuffing to claim affiliate commissions

Phia, the AI shopping-assistant browser extension co-founded in 2025 by Phoebe Gates and Sophia Kianni, reportedly engaged in “cookie stuffing” — silently claiming affiliate commissions on purchases it did not drive.

According to an investigation reported this week, Phia’s extension quietly opened a background browser tab during retailer checkout and swapped rival affiliates’ referral codes for its own, letting it collect a cut of sales other services had actually generated. The practice inflates a startup’s apparent performance while diverting revenue from the marketers who earned it.

“The most fundamental requirement in affiliate marketing is that commission is only paid if a user clicks,” said Ben Edelman, an affiliate-marketing researcher who flagged the behavior. Rival extension Capital One Shopping raised similar concerns.

Phia has raised about $43.5 million from investors including Notable Capital, Kleiner Perkins, Khosla Ventures and former Meta chief operating officer Sheryl Sandberg, alongside celebrity backers Sydney Sweeney, Khloe Kardashian and Hailey Bieber. The scrutiny lands as AI shopping assistants proliferate and compete for the same affiliate payouts that fund much of the consumer web.

A Phia spokesperson said the company learned within 24 hours that a recent code release “was causing misattributions from a subset of users” and had fixed it. The extension reportedly stopped auto-claiming referral clicks after July 7, 2026.

Affiliate platform Impact.com has suspended Phia’s account and is reviewing affected transactions, a move that could cut the startup off from a chunk of the retail programs it relies on. Phia has not said how much commission it collected through the disputed method or how many transactions were affected.

Whether the episode was a bug, as the company frames it, or a deliberate design choice will shape how investors and affiliate networks treat a company built around automated shopping.