Charging time does not reflect changes to charging rate

The planner puts me at a charger and says I need to charge for 16 minutes to add 25% SoC on a 103kWh battery pack. This is roughly 25kWh. I adjust the settings of a charger, setting the rate to 10kW and then replan, and it tells me it will take 18 minutes? I have no trust anymore in this app.