From the webpage:
Chrome extensions can be detected by fetching their web accessible resources. These are files inside an extension that can be accessed by web pages. The detected extensions can be used to track you through browser fingerprinting.
This is a pretty nifty tool to help illustrate browser fingerprinting based on extensions. When I open this in Brave on my Mac, I’m seeing that 0.002% of users share the same extensions with me, that seems like it would be pretty accurate for targeting.