BAT is Brave Attention Token, a form of crypto exclusive and locked into Brave. Its like a little crypto mining scam.
Brave Browser is funded by DoD: https://np.reddit.com/r/privatelife/comments/fe34ls/exclusive_brave_browser_funded_by_dod_contractor/
Brave traffic detected with Cryptocompare despite BAT rewards disabled: https://unddit.com/r/privacytoolsIO/comments/gr8nue/ (removeddit no longer works, use unddit)
Brave also has a known history of whitelisting Facebook and Twitter trackers, and has a crippled adblocker that does not work on Brave's "acceptable" advertisements.
Brave Browser hardcoded their crypto partner Binance referral links (https://twitter.com/cryptonator1337/status/1269201480105578496) alongwith Ledger and soon-to-be-compromised Coinbase (https://decrypt.co/31461/coinbase-wants-to-identify-bitcoin-users-for-dea-irs)
Also some new stuff you might want to check.