It is normal because it is the operating sound of the "relay" that switches the heater ON / OFF. The sound should be "clicking" when the brightness of the heater changes (when it gets brighter or darker).
BALMUDA The Toaster may be easier to switch to because it adjusts the degree of burning more often than other similar toasters.
When exemplifying the sound of a relay in other products, it is the clicking sound of the turn signal of the car.
