Your LG freezer has a drain in the freezer compartment to allow all the thawed water to flow out of the compartment, completing the defrost cycle. However, debris and dirt can block these drains over time. Without an access point to escape the compartment, water from the defrost cycle will begin to pool at the bottom of the freezer. This water will then freeze during the next freezing cycle.
Sometimes, the defrost cycle does not perform correctly. You may have refrigerant or compressor problems that interfere with the defrost cycle and thus lead to accumulations of frost. You may also have an air vent or air flow problem that prevents the warm air from being cycled throughout the bottom of the freezer, thus melting only the ice in the upper regions.
The thermostat regulates the temperature in your freezer, depending on the settings you have chosen. This thermostat uses several sensors, usually thermistors, to detect the temperature at different places in the freezer. The thermistors and the thermostat itself are both subject to malfunction or failure. This can lead to uneven cooling and defrosting, which can in turn create pools of frozen water.
LG refrigerators may encounter humidity problems, especially in wetter climates. This humidity can become trapped in the freezer compartments where it can form condensation and lead to extra amounts of frost on the bottom of the freezer, which the defrost cycle is not set to deal with. Increasing defrost times can help solve this issue.