The trim may be plated or coated, and an abrasive compound can remove that finish. First establish the material and whether heat caused the change.
What the observation means
A new mark beside a vent differs from ordinary fingerprints on a handle. Polishing before understanding overheating can hide useful evidence.
A useful next step
Check the care guide and use only approved cleaning. Report any nearby scorching, unusual heat or changed ventilation before further cooking. Do not assume exposed-looking metal is solid chrome or that a household polish is suitable near food and hot surfaces.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.