Also, to my knowledge Brave Software Inc. is a For-Profit organisation.
Despite those facts I am personally using Brave. In my opinion you already cut out most of the "bad stuff" of Chrome with this choice.
Any large codebase is nearly impossible to scour for this kind of thing, particularly a web browser which is an immense mound of source. There's so many ways to build in a backdoor, so many ways to build a way for you to later load a back door, that it's not plausible, even for a seasoned developer, to reliably find it.
You have to stop such things with source control. The surface area of a new fix or feature is much easier to analyze for vulnerabilities, intentional or not. I do this on a daily basis, and it takes work.
it seems that brave is setting the table for its own advertising once it has enough market share. the roadmap includes "opt-in" ads which will "respect your privacy". so clearly an advertising model is their source of revenue - exactly what people are switching from chrome to get away from. i personally don't buy into the idea that ads (which in the modern world are targeted) and privacy are compatible.