That’s easy- tax payers. The news coverage has said that the repair costs have already exceeded the developer’s liability insurance so the rest will bankrupt them and then it is on the city to pay for the rest (a shortfall of $20M is expected). That’s just for the repairs. In the unlikely event the building needs to come down (that is unlikely, to be clear), the city would definitely be paying 100% of that.
This is American Capitalism working as designed. Companies protect their owners and investors from any liability, and companies can simply go bankrupt and reform as another entity when costs get too high. Privatized profits and socialized losses. The American Way.