That means that websites that don't support https (as phereo.com) can't be accessed any longer.
Here the translation of the Mozilla site:
Mozilla has implemented an optional mode in Firefox 76, in which Firefox only accepts encrypted connections and tries to automatically upgrade unencrypted connections.
More than 82 percent of all connections by Firefox users worldwide are already encrypted. Put simply, this means that the connections are made via https: // and not via http: //. In the United States, this figure is already over 91 percent.
As of Firefox 76, users who want to play it safe in the truest sense of the word can set the dom.security.https_only_mode switch to true using the about: config configuration interface.
If you activate a URL without a protocol in the address bar after activating this mode, Firefox adds https: // instead of http: //. If a URL is entered that begins with http: //, Firefox automatically changes the protocol to https: //. Firefox also tries to load all sub-resources integrated via http: // automatically via HTTPS.
In this way, pages can be reached via HTTPS, which the user originally called up unencrypted, but in principle also delivers via an encrypted connection and is not automatically forwarded. Often, however, individual resources such as a third-party widget are only included unencrypted on pages that are loaded via https: //, although they would also be available via HTTPS. This is also automatically corrected in this mode.
Of course, an upgrade from unencrypted HTTP to HTTPS only works if the server also provides the respective resource via HTTPS. A fallback back to unencrypted HTTP, if a resource cannot be loaded via HTTPS, is deliberately not available in this mode. The name of the setting is the program here and it applies: only HTTPS.
Firefox 76 is scheduled to be released on May 5, 2020. The new feature is already part of the current Nightly version of Firefox.
The post Firefox 76 gets HTTPS-only mode first appeared on soeren-hentzschel.at .
Furthermore the operator of http://www.camp-firefox.de wrote me this:
The website operator must urgently be told what is going on with his page. In a few weeks, at the latest a few months, that would be it for all users of Firefox, Chrome and all other browsers. The deactivation of TLS 1.0 and 1.1 for early 2020 has been known since 2018 and has been postponed again solely because of Corona.
