SoC was 50%-ish, and I have the CAN logs + teslamate data to confirm that it just parks right at 120A. This car is definitely limiting just like the 3/Y. This makes sense because the architecture of this car is basically a scaled up Model 3. The busses/computer layout are very very close to the 3/Y.Your photo showed 120A x 427V. As I understand it, previous versions of Models X and S permitted 200A charging from this adapter, although of course the amperage would drop as the SoC rose. With the Model 3 and Y, the car limits the amperage to 125A. So the question is: What was your SoC when you took the photo? If it was low, then the Plaid may be doing the similar amperage limiting as the 3 and Y, which would limit the charge rate a bit. (I gather that the Plaid pack voltage is a bit higher, so the limit would be a little over 50kW.) OTOH, if your SoC was high, then the amperage may have been low because the car couldn't handle anything faster. In this case, it'll be interesting to know what happens at a lower SoC.
I actually typed up the 120A limit comment somewhere, but must have just imagined that I actually posted it here, hah. Anyway yes, the S/X now have this limit. If you search back, earlier in this thread I was able to charge my X 200A, which was like 75 kw with the adapter.