Just a small thought, but if there is any automation involved in determining these blacklists, I bet some of the keywords on Brave's site might be automatically classified as risky such as Tor Onion, Wallet, Crypto, malware. That might be enough to merit a default negative classification.
Not trying to excuse Microsoft, but there's other conceivable explanations (incompetence) here other than the obvious "Microsoft is trying to throw friction onto a competitor's business" (which remains a possibility, of course)
But it's pretty gross either way that these kinds of filtering lists would have such errors. Brave is probably ok either way, but what about a random small business that wrongly gets put on such a list? People are harmed by this level of carelessness from companies like Microsoft.
Haven't seen any other search/browser and Brave/search has been working fine for as long as we've used this web filter... until this morning