1. The secondary card shows that the primary card is blacklisted, which may be due to problems with the credit record or payment status of the primary card holder. Blacklist means that a person or entity is restricted or prohibited from certain rights or treatments because of violating laws, contractual agreements or credit rules.

2. Banks or credit card institutions usually evaluate the credit records of cardholders and blacklist or list bad credit behaviors.

3. If the main cardholder fails to repay the loan on time, violates the terms of the credit card or has other bad credit behaviors within the repayment period, it may be identified as a blacklist. This may affect the credit status of the holder of the secondary card, so that the secondary card will display the primary card as a blacklist.