A typical "proper" induction heating inverter has a safe operating area surrounded by about 6 limit lines.
( Capacitor Volt, Semiconductor volt Semiconductor current, Semiconductor temperature, rectifier power, turn off time)
During startup and load changes and ramp down,, each of these limits might be approached.
So there are 6 independent fast acting sensors/regulators. Any one can pull the firing frequency back into safe zone
With your cooking units they seem to be using just Semiconductor current, Semiconductor temperature.
When the pot is removed, for example, don't know, the drain voltage might fly up into danger zone while the Semiconductor current stays fairly constant.