SQL Server: Determine backup location from physical_device_name field
Does this StackOverflow answer point you in the right direction? Specifically if you look at the device_type column from the backupmediafamily table, what do you see? You can find the list of types in the API doc:

2 = Disk
5 = Tape
7 = Virtual device
9 = Azure Storage
105 = A permanent backup device.

I'm almost wondering if that's a CNAME or some sort of name reference to the actual path, but it may be dependent on the above.
This is likely the relevant part from the above answer to what you're seeing:

You should notice that these backups have value 7 in the column &quot;device_type&quot; (7 means Virtual device). These rows are actually very useful, for example it help to know that the Virtual Machine backups are running full database backups on a SQL Server instance.


There's no trace of these backup files since they are above the scope of the virtual machine (above the level of your machine) - these are triggered by the host (Hyper-V or VMware for example).