I use Clipple, the extended clipboard which allows you to store and paste multiple text items, extensively.
I’m also not sure that the Copy As Plain Text feature is working as it once did - I lost it in the upgrade, re-enabled it, but find it is not showing up when I right click. Arg. This too is crucial to my work.
If Mozilla no longer has this option, the lack of Clipple and Copy As Plain Text has too much of an impact on my work to remain in the Mozilla community - and that would make me sad indeed. Please bring it back soon!
Many thanks for your attention to these add-ons.