Occasionally when switching from incline mode to ERG I get a false 2000 watt spike on Zwift, but my Garmin does not get the same. This messes up my Ride Report graph, along with my power curve for a few months. I can use fitfiletools to strip out the spike for Strava, but it’s stuck on Zwift. There should be a way to correct this.
Your power graphs in Zwift show the same data used for category enforcement in racing, so they don’t let individuals manage that currently but you can contact zwiftpower@zwift.com to ask for help with it.
Zwift doesn’t create the power numbers. It trusts whatever the trainer reports. My trainer also reports 2000W spikes, if the power meters go to sleep (ie, stop pedaling for 5+ minutes then start pedaling). In my case I try to remember to bring up the pairing screen when waking them up but that won’t help in the scenario you describe.