We see in exceptional cases that the gas bottle freezes. The flame then goes out. It is because the evaporation of liquefied gas extracts heat from the bottle and the gas inside. If the gas bottle is small and the flames are high, the temperature will drop too much and freezing will eventually occur. There is nothing wrong with your gas fireplace. The height of the frozen moist on the bottle shows how much gas is left in the bottle.
If your gas bottle is frozen, you should wait for 15 – 25 minutes before turning the fire on again. A gas bottle smaller than 5 kg can freeze. This is unlikely with a gas bottle of 10 KG.