Firefox Desktop Browser 74 was released on the 10th March.
Firefox release schedules
Firefox release calendar
Mozilla provides two release notes. One is for users and the other is for developers.
Firefox 74 release note
From this version, firefox does not open web pages on TLS 1.0 or TLS 1.1.
Firefox 74 release note for developers
The release note for developers lists news and changes on APIs or developer tools that may be used by web contents developers or firefox plugin developes.
You can get overview of the new release changes and prepare to manage influence on WebClass functions or your learning materials.
Pickup for webclass
TLS 1.0 and TLS 1.1 is disabled by default from this version.
I think there is nothing special to do for using WebClass with new firefox.