Hey there!
These oscillations are due to the fact that your pedal stroke is not perfectly smooth in reality, and that is picked up on some trainers more than others. In other words, some trainers apply a smoothing factor to the data before they send it to us. This causes the graph and all the data we receive to be pre-smoothed.
We do not have a way to smooth the data that is charted on the graph at this time. TrainerRoad power smoothing only effects the Power readout and not the graph itself. Zwift likely allows for smoothing of the graphed data after it is received, which is why you see less oscillation on their platform.
At the end of the day, the oscillating power graph is more realistic and gives you some insight into the smoothness of your power stroke and your ability to maintain constant power. The more you focus on smoothing your pedal stroke, the less the Flux will oscillate, and the more efficient you will be at putting power to the pedals 