Why is TCP IPv6 preferred over QUIC IPv4

[sukunrt]

The draft says:

For example, if the first address in the sorted list is a QUIC IPv6 address, then the first TCP IPv6 address should be moved up in the list to be second in the list, then the first QUIC IPv4 address should be moved up to be third in the list,

1. Why is TCP IPv6 preferred over QUIC IPv4? Does this also mean that the dial delay to misconfigured IPv6 servers with a fixed delay is 500ms now?

2. What happens when there's only a QUIC IPv4 and TCP IPv6 address. I assume the preference is QUIC IPv4 over TCP IPv6, as the draft says. I understand, this ia a highly unusual situation.

The client SHOULD also sort the addresses in protocol order, such that QUIC is prioritized over TCP, as it connects faster and generally results in a better experience once connected.