Nothing. Modern ransomware has multiple methods to self-heal after a command and control server goes offline.

It’s been a bit since I’ve delved super deep in to it but at one time most modern malware has a whole list of domains to use. There is an obfuscated/encrypted algorithm in the malware that will try a list of domains based on a set of criteria. It can be reversed though. There are other methods as well(DNS, proxies, etc.) but previous was popular at one time.

Details are vague here so it could be a static C&C but it’s probably not. Rival ransomware gangs will also attack infrastructure in an effort to push them out or render their attacks pointless. So they attempt to make their infrastructure resilient from both seizure and attack.