Besides nearly every extension breaking (all for me, in fact), some websites are also broken. For example, Riot (the Matrix client) also fails entirely, making unusable: https://github.com/vector-im/riot-web/issues/11606
I would suggest that this is important enough to roll back to the previous package, based on Firefox 70, or at least to offer that version in the repositories. As it stands I'm completely stuck until a new version is released, short of using a flatpak or tarball or something.
