r134a
I'm no expert, so take this with a large grain of salt...
My understanding is that from a strictly security perspective, Chromium or even Chrome would be more secure than Brave. I think Brave does little that would improve security, and many things that could arguably weaken it. Certainly in terms of increasing attack surface, as noted above.
But most people care about more than just security, and Brave does a reasonably good job of improving privacy, without completely undermining the security model. So it is generally considered a good balance, but there are tradeoffs.
Just my thoughts.