TIL there is a name for this.

In 2002, during a press briefing about the Iraq War, Donald Rumsfeld famously divided information into four categories: known knowns, known unknowns, unknown knowns, and unknown unknowns. These distinctions became the basis for the Rumsfeld Matrix, a decision-making framework that maps and evaluates the various degrees of certainty and uncertainty.

Wiki page: https://en.wikipedia.org/wiki/There_are_unknown_unknowns