Relatively new to cycling, and I am a very surgey rider on and off the trainer. Off the trainer because my handleing isn’t great (working on that), but on the trainer my power isn’t smooth.
I am using PowerMatch with my stages and kickr core, and my power smoothing is set to 15 seconds.
Is It possible your saddle is set too high? If you are confident your fit is ok…
Single leg drills.
Beyond that there are some drills that may or may not help. Try emphasizing pushing the foot forward over the top and pulling back through the bottom. These are super subtle and more of a sensation you have to think about.
I use 2 second smoothing, my power also got a lot smoother when i switched to tubeless. That may not be everyone’s experience but for me it was night and day.