The reason that RV refrigerators need to be level to operate correctly is because the refrigerator uses ammonia and heat process to cool the refrigerator and the food in the refrigerator.
If the RV refrigerator is not level then the ammonia cannot flow properly throughout the tubes behind the RV refrigerator.
Even when the RV refrigerator uses electricity to heat the ammonia and not the propane heating the ammonia the RV refrigerator will not work properly.
An RV refrigerator will work some when not level but the RV refrigerator works best when the RV and the RV refrigerator is level.
So when you setup camp in your RV you need to make sure the RV is level from front to back and side to side.
Another thing about RV refrigerators is that gravity is very important to the RV refrigeration process.
Without it the ammonia liquid in the RV refrigerator will not properly flow to the evaporator coils to cool the refrigerator and food.