This was an HTTP/2 issue as well. IMO it was a big miss to not specify some kind of non-signed mode with opportunistic encryption. That is, if you set up an HTTP/2 (or /3) connection to a server that did not have a signed cert, it would do an ECDH exchange and provide guarantees that nobody was passively snooping on the traffic. Of course this would not protect against an active MITM but would be better than falling back to pure plain text.