The first one is realistic. The second one not so much. Why? Well, you don’t apply/generate power that smoothly. What you are seeing is artificial smoothing by the trainer.
In the case of the Kickr, there is/was a setting for a “ERG Mode Power Smoothing”. I think that is right. I have not had a Kickr in over a year. With that turned on, the graphs will look like your second screenshot. The same workout in ERG mode w/the setting turned off will result in a graph that looks more like your first screenshot.
As for your cadence issues, is it you or the Neo2 cadence sensor? Either way, check out the following: