That is a great question! Your configuration is stored on the Meraki cloud servers. It is not on your phone or any local device.
We handle the backup and restore at an infrastructure level within our company. There are numerous backup and restore safe guards that our site reliability engineers put in place to ensure the ongoing continuity of serving configurations to hardware is working.
In the extremely rare scenario there is an outage, your hardware will continue operating on the last configuration it was served from the controller on the cloud.