The tests were very clearly written to specifically highlight the approach to tracker blocking that Brave uses, by someone who likes that particular approach. It doesn't matter whether they are now open source, because that is still how they work, and how they were written. It doesn't matter whether that was before or after the person started working there, because their bias is extremely evident. Even if it were not so evident, of course the author of those tests will have biased them towards that browser. Initially because he liked it, but now because he works there, and would not publish anything that could be considered detrimental to his employer! He is clearly not going to publish something that shows a completely different approach can be just as effective in the real world.
This is similar to suggesting that our employee Ruarà is packaging Vivaldi as a Flatpak while completely unbiased towards us, since he is not being paid to do that as an employee. It is something he does on his own time. He does not do the same for any other browser. But ... he is not biased towards us, surely, right? Nonsense, of course he is!
The tests do not consider the approach used by Vivaldi, which is to block actual trackers. The test results summary refuses to show the results that Vivaldi gets in the real world with actual trackers, with the tracker blocker enabled or with the ad and tracker blocker enabled, and so does not reflect what Vivaldi can actually do. Instead, the tests insist that a browser must break legitimate websites, and then spend vast amounts of developer time trying to add workarounds fix individual websites that got broken in the process.
We are not going to switch to that approach, because it breaks lots of websites. You as a user then have to contend with broken websites. We as a development team would have to spend an inordinate amount of time patching websites, and there is no way we could check and patch all billion of them, so some would remain broken. Mostly the less popular sites that make up the majority of the web. We do not like that approach, and we are not going to use it. Our current approach to tracker blocking also protects you from profiling trackers, but has less chance of random breakage. Many of us have worked with a previous browser that was forced to patch a lot of sites that did not work correctly, and it is very costly in terms of development, and a never ending process that causes eternal frustration to users, until the patching can play catch-up with with malfunctioning websites. Our current tracker blocking approach is very effective. It causes less frustration to users, and takes less development time. It is not the only approach, but it is a good approach, and we are going to continue using it.
This has been asked and answered already (multiple times), and the horse is very dead now. You can put the whip away.
