Agree the Shanghai ramp was very fast, but COVID shutdowns have very much slowed down Texas and Berlin some.The model y was actually early. Shanghai ramp was fast. The only new new process is the stainless bending.
As for the only new process... I would count all of these and new processes that will take time to scale and perfect at volume:
4 wheel steering
possible drive by wire front steering
payloads much greater than any previous vehicle
Volume production of anything is hard.