You cannot track Monero transactions from the blockchain. It would be very impractical and takes too much time even for the NSA. So if this activity was detected, then it must have been either from the issuers of stolen credit cards or from the websites from which Monero was bought or sold.
But it's highly unlikely, almost impossible that they actually breached Monero transaction confidentiality.
What you are talking about is the key problem, the current situation with the conditionally anonymous crypto world. Let me put it this way: today, it is impossible to live in the modern world, fully providing for one's needs only with cryptocurrency, without crossing over into the world of fiat money.
Even having, let's consider, a qualitatively anonymous blockchain like Monero, a person is forced to perform actions that will de-anonymize him, as an example - withdrawal of funds from the exchange to card accounts....