Parents can set spending limits on the four main categories and at specific stores or freeze the child’s card at will, so you have final say on what the card can be used for. However, Greenlight itself prevents purchases in the following example categories to be made to keep kids safe (which is a common list of ineligible rewards purchases):
MCC 4829: Money Transfer
MCC 6010: Manual Cash Disbursements
MCC 6051: Quasi Cash Merchants
MCC 7800: Government Owned Lotteries
MCC 7801: Internet Gambling
MCC 7802: Government Licensed Horse/Dog Racing
MCC 7995: Gambling Transactions
MCC 9754: Horse Racing, Dog Racing and Non-Sport Internet Gaming