Not sure how accurate this is but from the google AI this is the answer
The 4GB weights.bin file is a component of Google Chrome’s Optimization Guide On-Device Model. It is used for Gemini Nano and is downloaded without user prompts. [1, 2, 3, 4]
This file is automatically managed by Chrome for on-device AI features. It is typically located at: C:\Users\Username\AppData\Local\Google\Chrome\User Data\OptGuideOnDeviceModel\ [1, 2, 3, 4]
How to Stop Silent Download/Remove File
-
Delete the File: Delete the
weights.binfile to recover space. -
Disable via Chrome Flags:
-
Open Chrome and type
chrome://flagsin the address bar. -
Search for “Optimization Guide” or “On-Device Model”.
-
Set “Enable optimization guide on device” to Disabled.
-
Relaunch the browser.
-
-
Prevent Re-downloading: If the file returns, you may need to disable AI features in settings or use registry edits to block “GenAILocalFoundationalModelSettings”. [1, 2, 3, 4, 5]
Why This Happens
-
Purpose: The
weights.binfile is used for on-device machine learning tasks (local AI), such as Gemini Nano, which allows the browser to process AI features without sending data to a server. -
Behavior: Chrome downloads this automatically when AI features are enabled. If deleted, Chrome may re-download it during a future update
Search prompt used was this
AI model file to disk without asking. The file is named weights.bin
Or the shortcut 
yay -R google-chrome
I’d be curious though, if the model is stored within the user’s home directory ~/, does it also get uninstalled?
Yer I’m not installing to test lol, if I could run a vm would be interesting to see what it gets upto
Anybody knows how ungooglled-chromium adresses this?
From what I found from a quick search it should not be there by default as this relies on google in the end
Have not tested or looked further. I would suggest looking at what features a browser offers and go from there to find what you need
It’s not the installing or even reinstalling of the model that bothers me. It’s that there’s no easy way to opt out, or that it’s not opt in.
Google, if you expect different by now I would suggest getting some pro help 
(just have a bit of a dig but use what works for you but there are a lot of other options)
Yeah, it doesn’t surprise me, but it saddens me 
Yer, it is sad but business is business sadly (I get ya)
Brave has recently released a new version of the Brave Browser named Brave Origin which is a clean version of Brave without the everything AI and Wallet etc… Only the blocker and sync. Normally on Windows and Mac its 60$ with 10 activations. Fortunately on linux it’s free. As a Brave user for long time i’ve switch to it recently. Note that it is still a beta at the time i’m writing this. I’ve been using it for the last 3 or 4 days without any issue.
https://support.brave.app/hc/en-us/articles/38561489788173-What-is-Brave-Origin
But there are plenty of other Browsers if you don’t want Brave for some reason like Helium which is another one. Comes with Ublock Origin and nothing else. No AI, no sync or anything else. You are full local.
Didn’t try this one yet but I have it installed. Both seems to run relatively faster and are snappier in my tests which are not scientific at all just my gut feeling YMMV.
Seen something about this yesterday, I’m yet to give it a try but am going to
Been using Helium Browser for sometime now, no issues here.
I use Vivaldi which is not going AI.
Good solution from all I have heard, I haven’t yet tried it
It’s a bit like the KDE of browsers - lots of options & preferences. I switched after Mozilla dropped the ball so many times in recent years, and wouldn’t go back now.