This extension works, but the devs logic is not the best. https://addons.mozilla.org/en-US/firefox/addon/save-all-images-webextension/

It creates a folder in the Download directory named after the site you're downloading from and then a zip file. see screenshots

Thanks for your response jonzn4SUSE! It seems like a lot of trouble to do something that, until recently, worked with a 'right click.' I wish someone on the Firefox team would explain what has changed with the browser to make saving GIFS no longer possible. Again, thank you.

Not a browser issue. Just search your issue and you'll see that... (queue the music) You are not alone.  ;-)) https://www.google.com/search?q=GIFs+%22saving+as%22+webp+only

Ah, yes! I've read all the blogs and appeals for help. The mystery still remains: why am I no longer able to do something that I was doing only two weeks ago. LOL!