Assuming that a misunderstanding makes your claim false, and no reason is given for it being a misunderstanding, it'sIt's the "just because" or "mother knows best" fallacy
Ipse dixit is an assertion without proof, or a dogmatic expression of opinion. The fallacy of defending a proposition by baldly asserting that it is "just how it is"
- You have misunderstood
- I have not
- Ipse dixit