F.B. Purity extension doesn't work on macOS

[vietthedev]

OS/Platform

macOS

Installed

OS/Platform's package manager

Version

146.0.7680.177

Have you tested that this is not an upstream issue or an issue with your configuration?

• I have tried reproducing this issue in Chrome and it could not be reproduced there
• I have tried reproducing this issue in vanilla Chromium and it could not be reproduced there
• I have tried reproducing this issue in ungoogled-chromium with a new and empty profile using --user-data-dir command line argument and it could not be reproduced there

Description

The extension doesn't work on macOS specifically. It does on Windows.

How to Reproduce?

1. Install F.B. Purity (https://www.fbpurity.com/install.htm) by any mean
2. Go to Facebook (https://www.facebook.com)
3. Login
4. Scroll and observe the page

Actual behaviour

The controls of the extension don't appear. The sponsored and suggested posts are not filtered out.

Expected behaviour

The controls of the extension should be available. The sponsored and suggested posts should be removed.

Relevant log output

Additional context

I'm on macOS 26.

Here's when it's working:

Here's when it isn't working:

[vietthedev]

So I looked into it myself and this is what I found: Facebook Purity script repeatedly queries posts with the div[aria-posinset] selector but for some reason the DOM structure on macOS is different. The script can't find such nodes so it doesn't work.

The weird thing here is that the DOM difference is only there with Chrome on macOS. When I change the user agent to another one such as Chrome - Windows or Firefox - Windows or even Firefox - macOS it behaves the same.