Unicast DNS has a home address. Anycast DNS has a home announcement: the same nameserver addresses are reachable from many places, and the network carries the resolver to a nearby available path.
The lookup should not have a region
If both of your nameservers sit in one network path, a congestion or attack on that path is a zone outage. Cloud DNS answers from 210+ Anycast servers so the authority is not a pair of VMs with pretty NS names.
DDoS is a DNS problem first
Attackers flood authority because it is a small target with a large blast radius. DDoS-protected Anycast is how the zone stays reachable when that happens.
Anycast does not replace records
You still enter A, AAAA, MX and CNAME. Anycast is how those answers are served. GeoDNS, weights and health checks still decide which answer a given resolver receives.
IPv6 and vanity NS
Authority should speak IPv6 as well as IPv4. Vanity nameservers can be branded while the same Anycast network answers underneath.