Hi, thank you for your feedback. You have understood the addon correctly. Actually, these tracking elements should be removed - and they usually are. However, there are technical restrictions from Mozilla for all URLs that belong to Mozilla/Firefox such as mozilla.com. These URLs must not and cannot be modified by any addon, so ClearURLs does not work on Mozilla/Firefox websites, but this is true for all addons.

You can deactivate these restrictions if you remove the affected URLs in the "about:config" from the "extensions.webextensions.restrictedDomains" setting.