In this case Firefox was first with a slightly different implementation (a warning instead of directly falling back to http). https://blog.mozilla.org/security

In this case Firefox was first with a slightly different implementation (a warning instead of directly falling back to http). https://blog.mozilla.org/security/2020/11/17/firefox-83-introduces-https-only-mode/ https://blog.mozilla.org/security/2020/11/17/firefox-83-intr... I think the idea originally came from the extension HTTPS Everywhere and its EASE mode back in 2018. https://www.eff.org/deeplinks/2018/12/how-https-everywhere-keeps-protecting-users-increasingly-encrypted-web https://www.eff.org/deeplinks/2018/12/how-https-everywhere-k...