It makes requests to API server that is deployed to k8s, which doesn't have a cold start. Clearly, some caching by the runtime and framework is involved here.

My point is that "cold start" is often more than just booting VM instance.

And I noticed not everybody understands it. I used to have conversations in which people argue that there is no difference in deploying web frontend to Cloudflare vs a stateful solution because of this confusing advertisement.

Likely reusing http keep-alive connections.