How to backup file to iCloud but not shown in iCloud Drive?

Question

I'm backup my database realm file to iCloud by using FileManage methods. Everything works fine, but there's a trick I want to achieve is:

The file should be backup by iCloud, but NOT shown in iCloud Drive.

For example, GoodNotes 5, we can open the iCloud in settings, verify it's truly backup in iCloud Storage, and the GoodNots 5 App File is not shown in iCloud Drive.

Below is my code that implement iCloud backup, but the App File ama will be shown in iCloud Drive:

private func retrieveLocalRealmURL() -> URL {
    let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
    let documentaryDirectory = urls[0]
    let realmURL = documentaryDirectory.appendingPathComponent("ama.realm");
    
    return realmURL
}

private func backupRealmToiCloudDrive() {
    let backgroundQueue = DispatchQueue.global(qos: .background)
    
    backgroundQueue.async {
        guard
            let ubiquityURL = FileManager.default.url(forUbiquityContainerIdentifier: nil)
        else {
            return
        }
            
        let iCloudDriveURL = ubiquityURL.appendingPathComponent("Documents")
        let iCloudRealmURL = iCloudDriveURL.appendingPathComponent("ama.realm")
        
        let fileExists = FileManager.default.fileExists(atPath: iCloudDriveURL.path, isDirectory: nil)
        
        func copy() {
            let localRealmURL = self.retrieveLocalRealmURL()
            
            do {
                try FileManager.default.copyItem(at: localRealmURL, to: iCloudRealmURL)
            } catch {
                printLog(error.localizedDescription)
            }
        }
        
        if fileExists {
            self.deleteExistedFile(iCloudRealmURL)
            copy()
        } else {
            do {
                try FileManager.default.createDirectory(at: iCloudDriveURL, withIntermediateDirectories: true, attributes: nil)
                copy()
            } catch {
                printLog(error.localizedDescription)
            }
        }
    }
}

private func deleteExistedFile(_ url: URL) {
    let fileCoordinator = NSFileCoordinator(filePresenter: nil)
    
    fileCoordinator.coordinate(writingItemAt: url, options: .forDeleting, error: nil) { deleteURL in
        do {
            let fileExists = FileManager.default.fileExists(atPath: deleteURL.path, isDirectory: nil)
            
            if fileExists {
                try FileManager.default.removeItem(at: deleteURL)
            }
        } catch {
            printLog(error.localizedDescription)
        }
    }
}