Some quick examples of things that often result in flagged accounts can be:
Using a VPN, Proxy Server, or other such thing to hide or fake your location. This is because it can be seen as you trying to bypass ad restrictions. Remember, advertisers pay so content is shown to specific regions. When you appear to be in a region you’re not, it is taking advantage of the system to see ads and receive BAT you shouldn’t be getting.
Modifying folders. There are some things you’re encouraged to do but some people do dig deep and try modifying folders that affect your encryption key OR where Users think they can fool the system into thinking they’ve seen more ads or have more BAT in their browser than they really do. Whether intentional or accidental, messing with the wrong things will get your account flagged.
Your setup sends mixed information to Brave. For example, maybe you’re in the United States. Your IP address shows you in California, your language is English-IN, and your time zone is correct. This will tell Brave you should see ads from India but then it sees that you’re actually in California. At this point it will think you’re trying to trick the system to see more ads and might flag you. If nothing else, it can result in you not getting BAT for ads that you do see.
Cloning your browser. Some people have learned how to do unofficial backup & restore and have the “great idea” that they can make multiple copies of the same browser on different devices and then Verify them with a custodial wallet like Uphold or Gemini. The system recognizes this and will flag the account and prevent anything from happening. Of course, even if unintentional, creating two exact copies of the browser and encryption key will be seen as attempting to do this and will flag you. So never have two identical copies of the browser running.
Uphold or Gemini identifies your account as fraudulent and/or there’s a violation of laws.
Any other type of suspicious activity is recognized by the system or Brave staff.
That said, just like people, the system isn’t flawless and mistakes can happen. If you haven’t done anything wrong, you can always create a ticket.