By default, the priority of every node is set as 0 by Stella.
Stella adapts an inverse scale to determine the priority: as the value increases, the priority becomes lower. In other words, any nodes with a value of -1 will have a higher priority than that of a node with 0.
Please refer to the documentation here for more details on the Node to Match & Priority.
You could also click here for common use of priority for Failsafe.