Frankly, their posts and updates are clear as mud -- can you identify what data is being transferred? I can't.
All I can tell for sure is that Mozilla is linking personal identifiers, and I don't know why they are claiming something in their blog posts that their lawyers won't support in their ToU.
See this post which surprised me: https://www.quippd.com/social/posts/2025/03/02/who-else-is-surprised-that-mozilla-uses-technical-and-interaction-data-for-advertising-purposes-on-the-new-tab-page.html
If you can show me how our data is used, that would do a lot to clarify things.