Its assigned function may have changed or returned to a default. The button's physical appearance does not reveal its current assignment.
What the observation means
Some models let the owner choose from several supported actions. A reset can therefore affect convenience without establishing a heating fault.
A useful next step
Check the normal settings menu and confirm the displayed assignment before use. Do not assume it still starts a familiar programme around hot cookware. If it performs uncommanded actions despite correct settings, stop using the feature and report the exact behaviour.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.