Root Ownership (root:root) of wp-config.php breaks wordpress with blank screen.

I am running a LEMP server with the Nginx user running as www-data:www-data. My wordpress installation is in /var/www/mcmo.is/. All of my files in my wp directory are owned by www-data:www-data. This setup works and my installation is functioning as expected. However, Now I am trying to secure my wordpress installation by making the ownership of wp-config.php root:root. When I do a sudo chown root:root wp-config.php, my website at mcmo.is no longer works and just shows a blank white page. Why is my website breaking when wp-config.php is owned by the root user and group? How can I debug and fix this so that wp-config.php is secured and unwritable by the webserver? Thanks for any help or suggestions.

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