Re: Who gains by this ?
Why assume it was malicious?
I can see a scenario where the FBI issued a notice to big tech firms to watch their supply chains carefully for threats introduced by state actors. That notice gets distilled in to a memo for people in to the company who need to worry about that kind of thing. The memo gets discussed by people who receive it and by some kind of (ahem) Chinese whispers process some confused underlings get the impression that it isn't just a warning but an actual active threat that the company is dealing with.
The leakers could have honestly believed what they were telling the reporters without it necessarily being true.