account being flagged for suspicious activity

You're card has been flagged due to suspicious activity, you may call Xbox to get it unflagged.

Okay, turns out this was an issue with the child profile being disabled for "suspicious activity." Logged into the account and it cleared up immediately.

Woopsie.

Hi BoubuhL8r! My name is Ricardo an independent advisor ready to help you with this situation!

Log in in the site it's being request, probably there's some suspicious activity on your account or you haven't completed the registration process for the account

If you are using a credit/debit card the issuer may have flagged it for suspicious activity (sometimes they do this at random it seems). So I would contact them and see if the card has a red flag on it.

You can also try another payment method (different card or a Paypal account, if you don't have one then borrow one from a friend or relative (with their permission of course), as long as the billing details are correct that should also work.

Every game of Face Off is being monitored, and any game that flags up as suspicious is being investigated by the Online Services Team. Just because in 1v1, there isn't any other player to report the boosters does not mean they'll not be caught.