A consistent location across comparable ordinary uses is more informative than a single irregular result. It helps distinguish the cavity pattern from a particular tray or uneven portion size.
What the observation means
The comparison must still account for mode, shelf, cookware and loading. A baking tray that is always pushed against the same wall can reproduce a usage pattern that looks like an oven defect. There is no need to deliberately burn more food to gather proof; notes from existing events are sufficient to explain the concern.
A useful next step
Describe the location in plain terms, such as rear left or upper shelf, and include the settings used. Keep any existing photograph of the result if helpful. Stop using the oven if the issue involves uncontrolled heat, smoke or electrical symptoms, rather than continuing to collect a more complete pattern.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.