Too much sugar will make the yeast grow too fast or too much, and that (or just too much yeast) will result in a dough with an unpleasant, yeasty taste. Too long a rising time can also cause a yeasty taste, so be aware of the rising time specified in your recipe and start checking the dough just before this time is up.
It is also called oral candidosis (or candiasis) because it is caused by a group of yeasts called Candida. Symptoms of oral thrush can include: white patches (plaques) in the mouth that can often be wiped off, leaving behind red areas that may bleed slightly. loss of taste or an unpleasant taste in the mouth.