I’m trying to figure out what could be going on here, because while a heavier flywheel will be more difficult to get spinning initially, once it’s rolling, it keeps spinning longer than a lightweight one, the effect of which is to feel a sense of momentum as you do actually riding a bicycle, particularly when accelerating from a stop, but also when you stop pedaling, the wheel speed doesn’t go immediately to zero.

So two things come to mind for me, your pedaling style (i.e. speed), and perhaps a poorly executed magnetic resistance which doesn’t modulate well.

At what RPM do you usually pedal? Do you vary the resistance through the course of the ride, or do you, say, set it to 5, start pedaling, and leave it at 5?