TLDR: This forces the tab icon on Notion pages to always remain as the Notion logo.
Notion pages have a feature where the page's favicon changes to match whatever custom icon is on the page. But If you are switching around between many other open tabs, that makes it hard to find the Notion tab again. Once installed, this extension simply prevents the favicon from changing whenever you are viewing a Notion page, making open Notion tabs easier to find at a glance.
Source code: https://github.com/leothorp/notion-favicon-fixer