Nonsense, AMD is getting more usable product per wafer, but clearly as they are constrained to fulfill market desire for Zen2, there will still be more than enough wafers ordered to keep TSMC happy.The chiplet design at AMD benefits AMD more than TSMC.
TSMC is a fab company - it is their business to fab silicon designs, not to demand that AMD fab larger designs that will yield less, as monolithic almost certainly will.
In short it is none of TSMC's business how their customers design things, they set a price per wafer and that is the end of it.