Anycast DNS doesn’t mean what you think it means.

Your DNS traffic to Cloudflare is routed via anycast. If Cloudflare is sending this DNS query (eg to an authoritative DNS server), the IP address it uses for this is not going to be the anycast one. These IPs are geolocatable and Cloudflare even publishes feeds of their approximate location. The response you get will be geolocated based on the IP that Cloudflare is using to send traffic to the authoritative.

Cloudflare explicitly does not use ECS (the edns extension to provide client subnets to authoritatives): https://developers.cloudflare.com/1.1.1.1/faq/#does-1111-sen...