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?
I don't follow.
If you're trying to find the individual site-specific permissions, you need to choose the "Connection secure" item that you have a screenshot of, then "More information", then "Permissions". It's not at the top level in a menu, but in a dialog.
As far as I know, it's been there for ages.