You are seeing this over ordinary HTTPS (TCP). The interesting version lives over HTTP/3.
This host runs an HTTP/3 (QUIC) server written in ~ATH, an esoteric language where all control flow waits for things to die. The entire QUIC transport (RFC 9000), packet protection (RFC 9001), and HTTP/3 + QPACK (RFC 9114 / 9204) are implemented in ~ATH itself; only the TLS 1.3 handshake and AEAD/HKDF primitives are delegated to OpenSSL through a small C shim.
This page was served by nginx over TCP as a fallback. This response carries an
Alt-Svc: h3=":443" header, so an HTTP/3-capable browser
(recent Chrome, Firefox, Edge) will transparently retry over QUIC on its next
visit — and then this page is replaced by a live one, generated by
the ~ATH server itself, showing real statistics about your QUIC
connection: your address, the negotiated cipher, packet and byte counters, and
handshake timing.
To see it now without a browser:
curl --http3-only https://quicdemo.dreamstation.systems/Source and details: github.com/robinpie/ath