In their announcement, Mixin wrote that "the database of Mixin Network's cloud service provider was attacked by hackers", leading to some confusion as Mixin is supposed to be a decentralized network that ostensibly shouldn't have a centralized cloud database.
Mixin announced they would be suspending deposits and withdrawals pending analysis of the incident. They also told users that they would be compensated "up to a maximum of 50%" on assets that had been stolen from them, and receive "tokenized liability claims" (that is, IOUs) for the rest.