"Debunked" as in no conclusive evidence was confirmed by 3rd parties. It could just as equally mean that investigators might not have found the needle they're looking for in the supply chain haystack.
Part of spy agencies' job is to plant news stories, so I find "just trust me, there's something substantial you don't know about besides the flimsy evidence we did provide" pretty hard to accept.
They'll also gag researchers if they think they might leak state secrets. Perhaps intelligence agencies know about adversaries' backdoors, and exposing them further would risk their current advantageous position in an arms race with those adversaries.
Debunked in the sense that the bloomberg article is a work of fiction. The authors wrote a "fascinating" story that has nothing to do with the real world. They assume backdoored resistors and other nonsense to make it impossible to verify their story akin to Russel's teapot.
Reality is boring. There have been supply chain attacks that installed malicious firmware or replaced pin compatible chips. That's not surprising, that's boring and old news.
