Wouldn't it be against the rules (Google, Mozilla) for a tab extension to send its domain to a third party site?

Question

Google

The extension shows whether the site in the current tab is included in the RKN registry.
To do this, it downloads the entire registry database and works offline.
But to display more detailed information about the blocking, you need to make an ajax request to the Internet and pass the domain name as a parameter. The domain is cut from the URL in the current tab with a blocked site.
By default, this will be disabled in the settings.
And the request will be made only by clicking on the extension button.

Answer 1

You need to read the rules.
IMHO: 99% of extensions work this way.