Server security doesn't allow to restore a backup

The host adds automatically mu-plugins that tighten up the server security. Because of this Managed Backups can't be restored. Getting a warning:
There has been an issue restoring fileset chunk 2: copy .../wp-content/mu-plugins/liquidweb_mwp.php): failed to open stream: Permission denied

After renaming the mu-plugins folder the backup is proceeding. Although the server creates automatically new mu-plugins folder