Here is the response I got from Elite.
"Please take note that Suito has a very accurate and precise power calculation, and by the flywheel inertia is able to correctly detect the different of push that you apply from one pedaling to the other
The fluctuation you have in fact is the difference of push that you apply on the pedals and depends also on the way and how smooth you pedaling is.
This fluctuation is not a issue or malfunction of the trainer but the consequence of its high precision.
To do a good training in erg mode, you have to keep a “smooth” cadence and try to have a good uniformity of pedaling. Eventually, our app in advanced settings there is the possibility to use avarage values (advanced settings - power smoothing)."