Setting the policy turns off Certificate Transparency disclosure requirements for the hostnames in the specified URLs. While making it harder to detect misissued certificates, hosts can keep using certificates that otherwise wouldn't be trusted (because they weren't properly publicly disclosed).
Leaving the policy unset means that if certificates requiring disclosure through Certificate Transparency aren't disclosed, then Google Chrome doesn't trust those certificates.
A URL pattern follows this format ( https://www.chromium.org/administrators/url-blocklist-filter-format ). However, because the validity of certificates for a given hostname is independent of the scheme, port, or path, Google Chrome only considers the hostname portion of the URL. Wildcard hosts aren't supported.
|Registry Hive||HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER|