Yeah, the BAT rewards is totally a scam. If you cannot use an external wallet your BAT earnings get eaten by exchange fees. I gave up on them for the same reason. I was still using the browser because of the effectiveness of their ad blocking system. 
With what I see on this thread its bye-bye brave. 

newnym

tech

The shady world of Brave selling copyrighted data for AI training

jinformatique

I quit using brave after they  screwed up my bats and I couldn't withdrawl to an external wallet.   So I have since quit joing the "bat" program. 