[CodeMichael]

Does that assume that all of the components (browser and server) support 1.2 as well? In a theoretical future state if I disable 1.2 on my browser doesn't that mean I won't trust a MITM box.

[agl]

> Does that assume that all of the components (browser and server) support 1.2 as well?

No: a client, server, and MITM proxy can all be exclusively TLS 1.3 and everything will still work(+).

(+) as much as it did with TLS 1.2, anyway.