Those power numbers that you are getting mean nothing (ie it is not close to real). The problem is that you can change the resistance knob of your exercise bike to 0 and Zwift would not know, and there is no way to calculate the power for a exercise bike because there is no power curve available.
The best will be to get a supported trainer and mount your bike on it.
If you want to use your exercise bike you will have to install peddals with a powermeter like Powertap P1’s.
have a look at this: https://zwiftinsider.com/are-your-power-numbers-accurate/