Now, happy eveyballs (updating RFC 8305) https://datatracker.ietf.org/doc/draft-pauly-v6ops-happy-eyeballs-v3/ One problem of happy eyeballs is that it hides problems (on purpose, but it does not help to solve the problems) so reporting is an issue.
Other issues: IPv6-only networks (more and more common) and choices QUIC vs. TCP (not just v4 vs v6).
So, the new algorithm prefers ECH then SVCB/HTTPS.