There may be zealotry involved in the attacks on Brave, but I don't think it is essentially OS/free software zealotry. Brave is open source, after all.

Edit: I am a passionate advocate for freedom, privacy, and free software and I like Brave.

It feels to me like even a nice comment about Brave is an outright threat to openness and virtue. IMO it’s the same bizarre Manichaean zeitgeist that pops up in so many other aspects of life and discussion.

Yes, I think we agree about the fact of an ideological bias, just not the underlying motive for, or nature of, the ideological bias.