On some designs, ice and airflow conditions can affect how cooling reaches compartments. The relationship is model-dependent and cannot be diagnosed from the two symptoms alone.
What the observation tells you
A blocked outlet, prolonged door opening or another fault may be involved. Removing the rear freezer panel to look for ice is not an owner check. A temporary improvement after shutdown also does not prove the underlying issue is repaired.
A useful next step
Record the ice location, timing and both storage conditions. Follow the model's safe guidance and arrange assessment, with appropriate food storage while performance is unreliable.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.