It's just spelling. It certainly wouldn't be better to think of it as HTTP/2 over QUIC since it works quite differently because it doesn't have an in-order protocol underneath it.
HTTP has a bunch of semantics independent of how it's spelled and HTTP/3 preserves those with a new spelling and better performance
HTTP has a bunch of semantics independent of how it's spelled and HTTP/3 preserves those with a new spelling and better performance