Tuya 3.0 Smartplug readings off by a factor 1000 (mA and kV)

I have two Tuya 3.0 zigbee smart plugs, bought on ali-express.
They are the white-orange type.

Integration in HA is via a Sonoff USB zigbee dongle. And they seem to work fine, except for the following:

  • Power measurement is correct (in Watts), but Voltage measurement seems to be off by a factor 1000. - Probably as a consequence, the current measurement is a factor 1000 too high (or, you might say it is in mA and the voltage in kV).
  • Cumulative energy usage does not seem to do much, although it could be the case that these are also off by a factor 1000, so i might get a reading of 0,1 MWh sometime in the future (i plugged in the water kettle to speed things up).

I am quite new to Zigbee and HA, so any help to get started somewhere is appreciated.
I’d like to find out whether these readings are in the “raw” output as communicated via zigbee, or is there a conversion error somewhere in the Home-Assistant software or some sensor configuration?