There are several reasons:

It may be that the cardholder's credit is abnormal, there are outstanding loans, or the credit card has been used less recently, so the cardholder needs to try his best to unfreeze it in the bank in order to resume the use of the credit card.

The card has expired, maybe the credit card has expired. If you don't pay attention to the expired card, it will also show abnormal status. Therefore, you must reissue a new card before the credit card expires.

There is a risk of credit card theft. When the credit card application platform thinks that the cardholder is at risk when trading and may be stolen by others, an exception will be displayed when swiping the card. It may be that the platform thought your credit card was risky before, so it froze your card on the grounds of students.