by default, front and none path is defined in the system.routing.yml file and it's '/'.
But me, this value is sync with one of my view path.
For exemple, in my page view "Xyz", if the path is "/x-y-z, the path setted in the database router table is /x-y-z. if i change it to /abc, after clearing cache the value in the database will be /abc.
If i delete the Xyz view, it will automatically sync the path value with an other view path.
I don't know why and i don't want that, i want it stay what the system.routing.yml file defined : "/". there isn't other front route definition in any file, in my theme or in some module.