This shouldn’t be too much of a surprise, as TLS 1.3 has been out for many years and is widely adopted.

I haven’t paid too much attention to the TLS WG lately (for obvious reasons if you look at their mailing list), but I assume this is mostly a “if you want Post-Quantum cryptography, you need 1.3”.

Makes sense. Nobody wants to deal with "this user-agent claims to support TLS 1.2, except this extension that was added in 2026" anymore.

If you're going to add or remove features, follow semver and bump that number.