I do not know the others but in my case, the answer is logical. Brave implemented the TOR system on one of its tabs. The people behind Tor advocate for human rights and tor is used as a method of privacy and against censorship, for the same reason it is used by many journalists and criminals. I don’t think brave would have implemented something that they themselves disagree with.
Although it would be best to wait for the official statement from Brave about this.