That sounds like nonsense. You can see the charging curve here: MG MGS5 EV Long Range charging curve & performance | EVKX.net
It stays above 50kW to over 80%, so you can do some simple maths.
64kWh * 0.8 = 51.2kWh
Let's say 10% loss, and starting at 10% is the usual quoted charge time, so we...