When I register Brave needed all my information and then why needs social security?
Probably the above will give you an insight.
Brave NEVER asks you for this information. So if you’re somewhere that’s claiming to be Brave and they ask this, then it’s fake.
That said, if you’re referring to Uphold or Gemini where you’re trying to verify, it’s because they are basically banks and the governments require what they call KYC (Know Your Customer) and AML (Anti Money Laundering). In this, those places have to verify who you are and where you’re money comes from by collecting information. Also since crypto is taxable, many governments require your crypto to be reported.