An integrated appliance may rely on a continuous ventilation route through the surrounding cabinet. The exit can be far from the compartment where poor performance is first noticed.
What the observation tells you
The location of a visible grille does not show the whole route. Storing objects above the unit or altering trim can obstruct the designed path. Opening a random hole lower down is not a verified substitute.
A useful next step
Compare the existing installation with the exact instructions and clear only safe loose obstructions. Have structural ventilation concerns assessed by a competent person rather than diagnosing the freezer in isolation.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.