The IETF is reserving the QUIC name for the underlying transport protocol, which has been separated from HTTP/3. Google's QUIC has them tightly coupled, so it's just "QUIC", whereas IETF QUIC is a general transport protocol (like TCP or SCTP, but technically implemented on top of UDP) for multi-stream connections, and HTTP/3 is a HTTP application protocol on top of QUIC.