The pan and, on radiant hobs, the surface retain heat. Reducing the selected input does not immediately remove that stored energy.
What the observation means
Heavy cookware and large liquid quantities respond differently from light pans. This lag is distinct from a zone continuing actively at full power despite a reduced setting.
A useful next step
Use the cooking method appropriate to the equipment and handle hot cookware safely. If control changes no longer affect heating as expected, stop relying on the zone and request assessment. Do not judge stored heat by touching the glass.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.