Brave doesn't have its own index of the full web, and it's even less useful than Yandex. And very likely buys some of it, according to what I've heard. So it falls into the last category.
do you have any reference for your claim?
i use brave search and find it very useful. very rarely there is something i can't find, and when i run into that other search engines are not much better.
Instead the wording leaves wiggle room for the possibility of using multiple.