“We also dislike shared state, so we’re not fans of distributed NAT installations.”
IPv4 addresses are expensive, and WARP needs egress IPs that look like they come from dozens of countries. So Cloudflare gives each data center one address and slices it between servers by source port. They call it soft-unicast. It’s NAT with better marketing. It works because Cloudflare owns the load balancer at both ends.