Earlier quoted context omitted.
https://www.benburwell.com/posts/configuring-cloudflare-univ...
That article doesn't address what I said at all. That's showing how to disable encryption on the backend (CF to Github) by selecting "Flexible". Looking at CF's help again and having used them a bit, there seems to be no way at all to enable full encryption (user-CF-github) with CF's non-enterprise offerings. This is because the request from CF to Github is still requested with your domain name (TLS and host header).…
So you can still get an encrypted connection without a verified certificate.