I think Ive got to the bottom of it.
When I first set up the Kickr one of the first things I tried to do was a Spindown/Calibration.
However when I tried to do it through the Wahoo app it gave me some info saying that calibration was automatic in the V5(I think thats my version, bought Oct 2020) and therefor a spindown was not needed as its constantly monitored. So I dont know if this means that eventually the Kickr would self correct/calibrate after some time of pedalling. (It didnt provide the option to calibrate)
Reading through the Wahoo troubleshooting I discovered theres a way to force it to do a factory spindown by clicking on its icon in the app 10 times.
Did the spindown and its much more realistic.
Thanks for getting back to me.