Foundry is shifting from a IDM1.0 strategy of permanent, sustained overcapacity to one where the capacity is determined based on proven demand.
That will take time and eventually involve selling at least the non-EUV fabs, badge flipping at all sites and continued reductions everywhere.
Expect this to be happening even as Foundry picks up meaningful external contracts. This is because most fabs have too many tools and therefore too many engineers and techs, even when run at capacity. That is how extreme the overcapacity remains, to this day.
TSMC doesn't have an army of people at each site for Yield and other fab support. That is done at the process level, not at the fab level.
#FAFO