It would be a [WAF](https://developers.cloudflare.com/waf/) rule
Cloudflare Docs
The Cloudflare Web Application Firewall (WAF) provides automatic protection from vulnerabilities and the flexibility to create custom rules.

HAN colo be operational? I'm living near that colo and it always seems to be 're-routed' to HKG. Sometimes Vietnam (actually 3 or 4 times a year) has some international outbound traffic issue and that affect on load speed on cloudflare CDN.
HANHKG