im a linguistics major so yes I am a nerd for knowing this buttt….

the two prefix “dis” and “dys” are two different things…”dys” comes from the greek language and means that something is bad, diseased, abnormal, or the opposite of the word. it is especially used in medical terms, like dyslexia. the word dysfunctional used to only apply for things relating to medicine or health, and changed to how it is in the current day can where it can be used to describe almost anything, like a relationship.

the prefix “dis” really translates into the word “apart” like it disassemble. so that’s why it’s not used in dysfunctional….hope that helped!