Using both Kaspersky Safe Kids and Cloudflare Gateway DoH DNS simultaneously might cause compatibility issues, as both services use their own certificates to filter HTTPS websites. This could potentially lead to conflicts or unexpected behavior. As for privacy, both services are reputable, but using two services means your data is handled by two different entities. It's crucial to review their privacy policies to understand how they handle your data. For security, both services aim to enhance it, but overlapping security measures can sometimes cause issues. It's recommended to test this setup thoroughly to ensure it works as expected.