Brave users of Tor tabs have a different fingerprint than users of the normal Tor browser. Having a larger anonymity set may be preferable for some people's threat model.
If you are among "did not download Tor browser" but are among "produces Tor web traffic without downloading Tor browser" you are easier to identify than if you were among "Downloaded Tor browser and produces Tor (web) traffic".
This would make you either more suspicious or your adversary (justifiedly) think you are an idiot.
Setting aside all the privacy risks associated by using a Webkit/Blink based Browser, using Tor inside Brave is like someone with a mask screaming "HERE I AM". Even though they have a mask on everybody sees you and hears you and your mask looks different to everybody elses so what's the point of the mask after all?
The mask only works if everyone is wearing the exact same mask. Which is the exact opposite of what Brave is doing.
