well, the tongue and the nose are both senses, and they are kindve like... attached so if your nose is stuffy then your taste buds wont work. i may have gotten this wrong but this is my memory from 4th grade.
Believe it or not, the mouth and the nose are linked together. So when you are congested or stuffed up, this affects your sense of taste just like it affects your sense of smell. Your sinuses are clogged up, and this causes problems and makes it difficult for your taste buds to function
its because bacteria in our nose where some of the bacteria from your cold is builds up and blocks nasal passages but i dont know why exactly not being able to breath through your nose blocks your sense of smell but it does.