I have felt for some time that Zwift does not read the correct values my Wahoo Kickr Core. Today I noticed that I get during a sprint briefly a high watt value (eg 490 watts). Shortly after reaching the peak, the value drops dramatically (in the example to 190 watts), although I keep the speed. Is it possible that this is due to a setting?
I tested the whole thing during a free ride.
Welcome to the forum.
It will be helpful to see the data, maybe a link to strava or a plot.
What I would assume is that initial power is to accelerate the trainer fly wheel, once the flywheel is up to speed it require les power to keep at that speed. This usually happens on flat roads and on slight downhill sections. Try doing the same on a slight uphill when the trainer has more resistance and you are not just pedaling against the flywheel inertia.
thanks for you reply. Today I rode stage 6 of the Tour de Zwift and had zeiweise 460 watts as peak directly followed by 98 watts and then again 340 watts.
My activity on Strava has the number 6605776587. Unfortunately I can’t post a link here on the forum. Maybe this will help 
This activity: 24.4 km Ride Activity on January 30, 2022 by Jonas L. on Strava
That just look like a small kick, where you done hard power stroke then back off.
Maybe someone else have a better explanation.