As it stands, adblocking is "post MVP"[1][2]. QR code scanning, however, is somehow part of the MVP. This doesn't make sense to me: there are many apps that launch the default system browser when scanning a URL QR code. You can easily get by without that functionality in the browser.
The comments in this post should be sending you really loud signal: technical users (the type of people who install preview software) don't consider a browser without adblocking MVP. You are drastically underestimating the significance of adblocking extensions.
[1]: https://github.com/mozilla-mobile/fenix/issues/96 [2]: https://github.com/mozilla-mobile/fenix/issues/2622 [3]: https://github.com/mozilla-mobile/fenix/issues/113