Whereas, Cryptonote one-time rings mix the payer amongst a group of payers with the requirement that it is publicly verifiable that each payer can only be spent one-time. The one-time key is manufactured by the Diffie-Hellman (ECDH) like exchange that creates a new stealth payee address on each spend and that stealth address can only be spent once. So the problem is that if your IP address is correlated across spends, it becomes possible to link stealth addresses together as the same payee and then start to unmask the anonymity set of the payer rings.