TSMC can handle a few months, even a couple of years, of weak sales, but that doesn't make continuous sales drops any less unpleasant.
As such, that a further drop in sales is expected from January-March cannot have gone over well.
True, the first quarter of every year is a slow season, but when the fourth quarter of the previous year also turns out to be a slow one (somehow), that is not as big a consolation as it would otherwise be.
At any rate, TSMC expects sales of CPUs/SoCs (for Qualcomm, Broadcom, Texas Instruments) and GPUs (AMD and NVIDIA, obviously) will fall by an overall 7-11%.
All the major clients mentioned above have reduced their orders, since they, too, are adjusting their inventories.
NVIDIA and AMD haven't cut down on their demand much because the latter's Radeon HD 8000 series is almost out the door, and NVIDIA needs to make sure it has enough GPUs to match its rival's push.