Cloudflare API ips Endpoint seems to ignore ETag

When running the command

curl --etag-save etag --etag-compare etag https://api.cloudflare.com/client/v4/ips -v

curl --etag-save etag --etag-compare etag https://api.cloudflare.com/client/v4/ips -v

curl --etag-save etag --etag-compare etag https://api.cloudflare.com/client/v4/ips -v

curl --etag-save etag --etag-compare etag https://api.cloudflare.com/client/v4/ips -v

twice, I'd expect that the server would return a

304

304 status for the second request.
However, both requests return a

200

200 status + the full mesage body.