This is going to happen, what with the internet and all.
To guard against this, I load all the gpx files for my trip into a cloud drive and then make them available offline. This is in addition to keeping the offline routes in MRA.
Then in the event of an outage I can load into another app to navigate.
I started doing this after the stupid Garmin Explore app deleted all my TET France routes and tracks on my Montana, then synced back and deleted them from the cloud….