For such a tiny incubator it is a huge fluctuation, personally I would not rely on the internal thermostat.

I always recommend a separate (reliable) thermostat with the probe placed in a dummy egg box (set up like any other egg box) placed in the center of the incubator.

I will assume that those are the temps in the incubator itself and not in the egg box, which means the temp inside the egg box is likely above (remember eggs also generate heat).

I would double check the temps in the egg box with a temp gun?