Followup to 'current flow rate'

The GPM value responses to the 'get current flow rate' query does not correspond to the values in the app dashboard; eg while the clothes washer is filling I am seeing a few minutes of ~2.5 GPM via API polling and the dashboard shows ~3.8 Gallons in the 'per minute' bar graph view for the same time span. The ratio doesn't suggest an obvious (to me) unit disagreement; what explains the different values?

Thanks