You can pick any number you like. One EV site says it's 67 but when I queried them by email it turns out they simply guessed at 5% over. Geez...
In the pic above it say 360 V, so at 180 Ah (Hyundai's number) that's 64.8
In the emergency response info it's quoted at 352.8 V so that's 63.5
In Hyundai's VIN info it says 356 V so that's 64.1
The bottom line is that it's entirely dependent on what voltage you pick as the average over the allowed operating range. Normally that's somewhere between 3.6 to 3.7 V per cell for Li-ion (there are 98 sets of three cells in parallel) so that's 352.8 to 362.6 V and 63.5 to 65.3 kWh.
It's unclear if 0-100% is actually 64 kWh and if the battery adapts to maintain range as health drops.