A good majority of people use some form of United Health as part of payments and claims to doctors and other health related things. The company may have paid two different ransom payments one to BlackCat which played an exit scam later, and another group who removed United from their victim site after payment.
They claim to have paid to protect our data, but this is not necessarily the case.
UnitedHealth confirms it paid ransomware gang to stop data leak is the article that covers this in complete detail.