If your IP address is leaking even with Secure DNS (DNS over HTTPS or DNS over TLS) enabled, it could be due to WebRTC leaks, improper DNS configuration, or browser settings bypassing secure DNS. WebRTC can expose your local IP address, even with a VPN or Secure DNS, and DNS settings might default to regular servers despite the secure configuration. To prevent this, you should disable WebRTC in your browser, ensure your DNS settings are correctly configured, and use a VPN for extra security. Running DNS leak tests can also help confirm if your setup is secure.