Something like "quote unlinked" is more terse/cryptic/technical, but at least it's something people will have to look up the meaning of, rather than misinterpret by default.

I find “quoted user” more difficult to understand than “original author”.

They can't just say "hidden by user XYZ"?

Then it's not clear that the named user is also the author of the quoted post, and moreover it could incite harassments against the now exposed user.