Not on every model. Some push-in knobs are designed to sit flush in more than one position, so their appearance alone may not prove that heating is off.
What the observation means
The indicator mark and the manual's stated Off position are more reliable. A knob that no longer pops out or turns normally is a different issue from a deliberate flush design. Force can damage the control or obscure the selected position.
A useful next step
Check the markings while the appliance is safe and cool. If you cannot positively select Off, use a safely accessible isolation control and seek help. Do not grip the spindle with pliers or continue using an uncertain setting.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.