Folks,
New Neo 2T owner here, Vortex previously.
The power signal when in ERG mode is awful:

When compared to the Vortex this signal is all over the place and more than 10% off from the ERG target.
0.0.36 firmware. Please advise.
The power graph is looking like this because it is your real power, your cadence is fluctuating, the pedaling isnt smooth and circular, thats all. The Vortex is showing fake ERG power chart (showing the target as a straight line) and not your real power output. Try to pedal smoother with steady cadence and the power chart will be smoother (but never will be totally straight , 2-3watts up and down is always happening with perfect pedaling style also)
Are You doing the ERG workouts on small ring front (and middle at rear) or on big ring front?
Here it is one of my latest indoor ride from March:
https://connect.garmin.com/modern/activity/4654720075
Ok, i'm using Neo since 5 years and have smooth pedaling style (outdoor also) but everybody is able to reach this smooth chart with lots of practice.