Does anyone else notice that when using the smart plugs, the "Cost" to use them is always made against the current tariff even if all the energy is coming from either the solar or battery?

i.e. I have just charged 7kWh on a plug and its showing £3.54 but every bit of that came from solar so it didn't cost me that at all (if anything you would argue the cost is equal to the export I have lost but thats also a different number) . It makes it really hard to track what something is costing in ££ to be run.

Is this a bug that GivEnergy can fix?