Running those adblockers on your devices is extremely insecure. They register as a VPN and intercept HTTPS traffic. They decrypt the encrypted traffic, filter it, and encrypt again meaning all your communications are signed by this single app’s certificate. Not to mention any vulnerability would wreak havoc.
I gave you the real reason it should be controversial. Brave’s fuck ups have not been significantly worse than other companies’.
re: open source In theory: yes. In practice: maybe. It’ll probably eventually be caught by some researcher but unlike popular belief all open source code bases are not constantly being audited by the community. A random person can’t just read Brave source code for all platforms and accurately gauge if they’re doing something nefarious. It is very easy to hide stuff in code or misuse a protocol for evil purposes, etc.
You can modify the source code but as evident by the fact that there’s no Brave fork with crypto removed (there was one but their branding was too similar to Brave’s so they got sued), it’s not an easy feat to maintain that.