They're all manufactured in Taiwan/China so these companies recieve plans well in advance to prepare their production lines. And they have no loyalty, because you have to use them or else. It's the same for Apple or PC hardware rumours.
The details start on Chinese forums or hardware "review" sites. Sometimes the Taiwanese companies leak for PR purposes, e.g. they are unhappy with Nvidia so instead of telling them they leak their stuff until paid to stop.







