Sonoff powct / pow ring power not accurate

Good day,

I flashed my Sonoff POWCT with ESPHome. The relay works perfectly, but the power accuracy is most definitely NOT correct. I tested it with an electrician. I have 2 units, one has ESPHome and the other is stock with the Ewelink app.

The mains measure 235w and when the 3kw geyser kicks in, the house measures 1183w. The device with the stock firmware measured over 4kw. Oh and when exceeding the 4kw, the ESPHome flashed POWCT actually drops it’s reading to 537w

Can anybody kindly please point me in the right direction? I tried flashing to Tasmota, but apparently that’s not possible.

Kind regards,