If you read the post covering the feature in Brave, and reviewed the screenshots of its implementation, you'd see that the intent here was to respond to user input, and
offer the user the option of using Brave's referral link. The intent was never to
coerce users into using the link; it was merely presented as an option—a clean and clear way to support Brave development.
It is still an example of traffic attribution, as is the case with Firefox sending your keystrokes to Google asynchronously (marked with the Firefox identifier). This is how Firefox continues to get paid, by sending users over to the Google search engine. In the case of Brave, this identifier was shown to the user prior to any network activity. That isn't the case with Firefox (and nearly every other popular browser).