There were suspicious events that signal that something is up, like when Apple completely switched from Supermicro to other vendors or when they started to develop processes to prevent supply chain hardware attack around time when CIA supposedly found the bug (2015-2016).
iPhone is also switched from Qualcomm modem to US designed and fabricated by Intel.
Also, their work on supply-chain security is also at the same time that Apple was more publicly promoting the security of their own hardware. So those two things could be entirely co-incidental.
That said, short of a release of internal documents, I don't think anyone outside has a decent idea of what's going on.
Qualcomm is based in San Diego, CA.
In other words, they said nothing at all.
Under the First Amendment Supermicro would have to prove actual malice—that is that Bloomberg knee its reporting was false or acted with reckless disregard for the truth. That’s a very difficult standard to meet.