It doesn’t stop growing and then propagated itself at the bottom. What do I do?
It looks fine but if it is getting too tall you can propagate it by cutting off the top and replanting it. Here is more:
https://www.gardeningknowhow.com/houseplants/dumb-cane/propagating-dieffenbachia.htm
https://www.gardeningknowhow.com/houseplants/dumb-cane/growing-dumbcane-dieffenbachia.htm