A thermometer should be positioned for the storage conditions you want to assess, not simply wherever its display is easiest to see. The light housing and door area may be unrepresentative positions.
What the observation tells you
Opening the door to read a device can expose that corner to warm air, and the light may operate only while the door is open. The exact effect depends on the appliance and lamp design. An isolated result beside a fitting should therefore not be used to condemn a temperature sensor or control without a better comparison.
A useful next step
Use the thermometer's placement instructions and the appliance guidance, record its location and keep the door opening brief. Do not tape over switches or hold a door sensor to simulate a closed cabinet. If the light seems to stay on abnormally or its fitting is damaged, report that observation separately.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.