The FTP and SFTP backup transports do not support transferring metadata, so it is necessary to disable metadata generation when using those transports. Additionally, if you're backing up to a NFS mount, the metadata must be disabled.
Please note, cPanel does not support backup to NFS filesystems. NFS filesystems can cause issues if connections to the server are interrupted.
Can I use NFS mounts for backups?
The only way to disable metadata generation is through the WHM API:
whmapi1 backup_config_set disable_metadata=1