Not disappeared actually, but it was whittled down so much it might as well have.
Let me show you the site-specific permissions menu that I'm talking about
In an ancient version of Chrome:
Here it is in a modern version of Chrome:
Here it is in Edge:
This is what it looks like in Firefox:
And this is what it looks like in Librewolf:
How do I get the good version back?
If you open the spoiler, you’ll see what I’m talking about. Firefox used to have one similar to Chrome, but now it’s whittled down.