The TSMC Arizona fab phase 1 capacity is intentionally to start smaller than other TSMC Gigafabs. In terms of efficiency and cost it's probably not as good as other those Gigafabs too. But it doesn't mean it won't make enough profit to justify the effort. Because the smaller capacity, TSMC can easily push the utilization rate to very high with the support from Qualcomm, Apple, AMD, Nvidia, and Broadcom. For each of these TSMC US customers, to allocate a small percentage of their global orders to TSMC Arizona is easier because this smaller capacity.
This start small strategy will help TSMC, US government, and TSMC's customers to ensure a successful outcome.