https://www.bleepingcomputer.com/news/software/mozilla-overhauls-content-blocking-settings-in-firefox-65/

In Firefox 65, Mozilla is overhauling how users can configure the Content Blocking settings. With this version, the previously confusing configuration is replaced by three different modes that a user can select that offer varying degrees of blocking and customization.

The biggest change is that the Content Blocking settings under Privacy & Security. Firefox 65 will now offer three different modes that users can select; a standard, strict, and custom mode.