This is what I've done after spending some time to look into it, this is for Linux Desktop:

Delete Chrome's silent 4 GB AI model file and AI

In Chrome, go to: chrome://flags

  Search for and Disable these:

  Enables optimization guide on device

  Prompt API for Gemini Nano

  AI Mode

Open DevTools (F12 or Ctrl+Shift+I).

  Click the Settings (gear icon).

  Go to AI Innovations and uncheck Enable AI assistance.

For Linux, in a bash shell, this should prevent Chrome from trying to download the file again because the root user instead of my user, will own the file/directory.

  sudo rm -rf ~/.config/google-chrome/OptGuideOnDeviceModel

  sudo rm -rf ~/.config/googlechrome/Default/OptGuideOnDeviceModel

  sudo touch ~/.config/google-chrome/OptGuideOnDeviceModel

  sudo chmod 400 ~/.config/google-chrome/OptGuideOnDeviceModel

  sudo touch ~/.config/google-chrome/Default/OptGuideOnDeviceModel

  sudo chmod 400 ~/.config/google-chrome/Default/OptGuideOnDeviceModel

In case they already existed from doing the above previously, make sure root user owns them.

  sudo chown root:root ~/.config/google-chrome/OptGuideOnDeviceModel

  sudo chown root:root ~/.config/google-chrome/Default/OptGuideOnDeviceModel

List to check them.

  ls -l ~/.config/google-chrome/OptGuideOnDeviceModel

  ls -l ~/.config/google-chrome/Default/OptGuideOnDeviceModel