AFAIR QUIC has the same number of round trips as normal TLS if you set the TCP options right. Basically it shaves off RTs because it begins the TLS handshake in the SYN. You can do that with TCP, too, doubly so if you aren’t using a TLS library that sets socket options for you. The claim in your diagram that you need 0 full RTs to do QUIC setup is nonsense, that’s just if you’ve spoken to the server before and it has cached keys, but the 0 RTT TLS stuff isn’t being implemented in generic HTTP stacks because of replay issues.