the only case when it corrupt drawing is when the ellipse is more like a line then an ellipse, when one of the axis is barely moving while the other taking the full speed for the next step.
Yes, thats what I meant.
An algorithm sould be univeral and not break when it comes closer to extreme settings.
https://www.geogebra.org/m/AAx6FWka
If the dot is on top side, each of its step is maybe set to be dense enough.
If the dot is in right side, anbd the ellipse not very high, then the density will increase a lot, perhaps too dense.
Either you can accept these changes in density, or you try to optimize it in each step.
The whole world is a compromize
Maybe one solution would be to divide the ellipse into sections, where its equal to circle, where its more dense and where its not so dense, for switching to different optimized algorithms in each segment.