Holding already frozen contents cold is a different task from removing heat from a large new batch. The cabinet's litre capacity does not describe how quickly it can freeze fresh food.
What the observation tells you
Package size and placement also affect the process. A single deep warm container can be demanding even when it occupies little space. Turning to the coldest setting does not abolish the manufacturer's loading limit.
A useful next step
Use the model's freezing-capacity instructions when batch cooking or accepting a large delivery. Keep newly prepared food within safe cooling guidance and arrange another suitable freezing option when the load is excessive.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.