A shopping bag is not equivalent to freezer-suitable food packaging. It may provide neither the required moisture barrier nor appropriate food contact.
What the observation tells you
Paper can become damp, tear or stick to frost, leaving the contents exposed. Outer packaging can also carry dirt from transport. Using it to group already sealed packs is a different purpose from wrapping uncovered food directly.
A useful next step
Follow the food and packaging instructions and use clean suitable bags or containers for direct storage. Keep outer grouping material clear of vents and door seals. Check that labels remain readable without prolonged searching with the door open.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.