It is due to high temperature. If you want to make 100gm candle then take 300gm wax in vessel n melt only 100gm of it, it will help to maintain temperature and whitespots will not appear
Please don't fall in these candle. They put a very small amount of soft wax an the candle is made. approximately 50 gms. I have already paid a good price an burnt my hand. So you people don't spend your hard earned money which can be useful in the time of covid