When setting up the scanner with the “Prepare Analysis Configuration” task, we are required to enter the “Project Key” as well, but from what I know each service connection is limited to a single project. So is there a reason why the Project Key is also required or is it possible to use the same service connection for different projects?
Service connections are not limited to a single project! The same service connection can be used for any project where the token provided to the connection has Execute Analysis permissions.