The media family on device incorrectly formed for read only file group restore Yes the databases (source and destination) are the same version.  I have checked 3 times.  Both are &quot;Microsoft SQL Server 2019 (RTM-CU8-GDR) (KB4583459) - 15.0.4083.2 (X64)&quot;
The database itself restores ok without error.  Only when I try the read-only file group restore does it give the error.   I have redone the back up and attempted the restore again just in case I had something wrong with the backup.
I have done this numerous times with ss 2016 and even when upgrading from ss2016 to ss2019.  But now I am testing the restores it just looks broken to me.  Almost like this is a  bug
I think you have encountered a problem with disk sector size, the old (very old) standard was 512 bytes per sector and the new one is 4kb. When you restore a database between these 2 standards the restore re-writes the data to 4kb sectors but with a read-only filegroup my hypothesis is that this would not be allowed. There is a basic discussion of the change here :-
https://techcommunity.microsoft.com/t5/sql-server-support/sql-server-new-drives-use-4k-sector-size/ba-p/316277