Google’s Chrome quietly drops a 4‑gigabyte file named weights.bin into macOS’s hidden Library folder, enabling the on‑device Gemini Nano LLM without user notification. Computer scientist Alexander Hanff exposed the download on his site The Privacy Guy, noting the file appears after a Chrome update and re‑downloads after deletion each time.

The file lands in a folder most users never access, and its generic name masks its purpose. Hanff reports that deleting the directory triggers an automatic re‑download, a loop that only stops when AI features are disabled via flags or enterprise policy—options unavailable to ordinary consumers for regular users daily.

Beyond privacy concerns, the hidden download raises environmental flags. Hanff estimates that a mid‑band rollout to 500 million devices—roughly 15 % of Chrome users—would emit about 30,000 tonnes of CO₂e, matching the yearly output of 6,500 cars, not including subsequent model updates for the tech industry to reassess data usage practices globally.

Google has not yet responded to inquiries, and the company’s silence fuels speculation that the move was an oversight rather than a deliberate push for on‑device AI. For users, the lesson is clear: verify hidden files and consider disabling AI features if privacy and energy costs matter for every day.