As the name suggest post-launch support service is the service that a client often expects from the service provider after the project has been released. This service includes the maintenance of the project.
Now, if we discuss in the terms of reliability then Hiring an App Developer Team is more reliable when it comes to post-launch support service. App developer team consist of skilled members which include full stack development, project management and many more, which enables them to work fast and effectively on post launch services. Whereas hiring a freelancer often work alone, there is no team which will focus on post launch issues.
Moreover, freelancers are committed to multiple clients, so it would be time taking to provide immediate fixes.