Yep. However, it's still clocked faster (with or without SMT).
I can only think of two things here:
Tooling:
If it does come down to immature Microsoft tooling, then they royally fucked up. (Given how much better their BC support is, I would like to think this isn't the case)
TDP:
The SOC is being thermal throttled.
Can't be thermally throttled, the XSX kept a locked 60FPS on Gears 5 which is technically more graphically impressive when DF was testing the wattage of the system. There isn't a thermal issue, as that scene was pushing XSX to its highest possible temp at the time... do you think AC V is pushing wattage above Gears 5 and hitting a thermal limit? I doubt it TBH...