Here's a YouTube video by Byorn Nyland testing fast charging on the I oniq Electric (again).
He gets the same results as all the posts above. Max power is about 67kW.
But he seems to think there is still the possibility that this is the limit of all current chargers, not the limit for the car.
The advertised limit for both the I oniq and Soul EVs is 100kWh, but no one has ever achieved this.
Perhaps we have to wait for faster charging to become available.