Contrary to what you might expect, your fridge’s freezer compartment is not supposed to be covered top-to-bottom in ice. The freezing temperature in your freezer is supposed to be a dry cold, maintaining a uniform temperature that doesn’t allow water vapor in. Therefore, if you do start seeing a lot of ice, that’s a sign that your freezer isn’t being properly regulated.
This can be caused by a defective freezer door seal or a problem with the fridge’s internal temperature regulation system. Whatever the case, if your freezer is icing up, it can put whatever food you’ve got in there at risk of completely solidifying in an icy prison. Depending on the make, model, and year of your fridge, you may be able to either physically defrost it with an ice scraper or run an internal defrosting program, so it might not be a sign of looming danger, but it’s definitely something to keep an eye on.