@marten-seemann can probably answer this
It's gQUIC. IETF QUIC doesn't have browser support yet, so there's no point in deploying it on the server side yet.
Caddy 2 will support IETF-draft-compatible HTTP/3, very soon: https://github.com/caddyserver/caddy/pull/2727
Most helpful comment
It's gQUIC. IETF QUIC doesn't have browser support yet, so there's no point in deploying it on the server side yet.