Great add-on but if you could control things at a finer-grained level (i.e. form history vs all history) it would be perfect.

Tut was es soll, einfache Bedienung

I'm using this to block the DeepL and Google Translate subdomains (which would generate URLs every time I changed my input) and it works just as I hoped.

There is no regex support, and the Full URL matching mode is a bit problematic, as the URL has to be an exact match all the way down to GET parameters (?foo=1) and even the anchor (#foo) at the end. Also if you input a full URL without the protocol (e.g. https://), it may inadvertently omit the first character of the subdomain you typed.

If this add-on had regex support or a whitelist containing full URLs that the blacklist shouldn't block, I would rate this 5 stars. As it stands, any subdomain I block doesn't get suggested or auto-completed in my address bar, which is a good thing for privacy but a bit unfortunate for my use case.

This works in Firefox Quantum! :)
Just go to the webpage you want to have forgotten and open the context menu anywhere on the webpage.
Then hit the button "History Block" and block this site --> Done

Find the extension very useful but preferences panel no longer popups since the extension was upgraded to reflect "Firefox add-on technology modernisation"