Version disclosure + weak header posture on the API edge.
The TLS endpoint discloses the upstream proxy version in a response header and is missing two of the four expected security headers. Combined, this gives an attacker an unusually precise fingerprint and removes a layer of in-browser defense.
GET / HTTP/1.1Host: api.example.comHTTP/1.1 200 OKserver: nginx/1.21.4 <-- version disclosedcontent-security-policy: <missing>strict-transport-security: <missing>