To expand on this:
• QUIC’s original implementation bound the transport protocol & app protocol to HTTP/2 - this was led by Google and is commonly referred to as “gQUIC”. This is what Chromium implemented and could be used via the Cronet library in other contexts.
• A desire to use QUIC as a stand-alone transport layer (above UDP) grew, and is now standards-tracked as “IETF QUIC”.
• HTTP/3 is a evolution (rather than a revolution) of HTTP/2 that requires IETF QUIC as a transport.