Chrome’s latest update quietly drops a 4 GB AI model onto Macs that haven’t asked permission. The file, named weights.bin, powers Gemini Nano, the engine behind scam‑detection, autofill and the “Help Me Write” feature. Users notice their storage shrinking, but Google never flagged the download, leaving many unaware of the hidden cost for everyday browsing tasks and for developers using it today.

Security researcher Alexander Hanff uncovered the issue after noting that Chrome installs the model on any device meeting minimum hardware specs, regardless of user consent. The build that introduced the file is 148.0.7778.97, and the model resides in Application Support under OptGuideOnDeviceModel. Users can confirm its presence by checking the file size of weights.bin in the Finder for inspection today easily.

Simply deleting the file triggers Chrome to redownload it on the next launch. The permanent fix is to turn off On‑device AI in Settings → System, or disable relevant flags at chrome://flags. Disabling the model also disables Gemini‑powered features. Users concerned about silent downloads may opt for a different browser pending a more transparent update from Google in future releases.