There could be several reasons for this. If you leave your moka pot sitting on the burner for too long, it’s going to make your coffee taste burnt. More importantly, it could be because of the temperature of the water you fill in the pot. Water for the moka pot should always be preheated and poured in so that the coffee doesn’t sit on the stove for too long. With hot water poured in, you’ll be able to brew the coffee quickly, lowering the possibility of it tasting burnt.