Dispargender is when someone feels like they do have a gender, but it is missing. It is different from agender because they do not feel like they don't have a gender, just that their gender they did have is gone.
History
The term was coined on January 14th 2021 by fandom user Lunarblema and the flag was made on the same date by the same user.
Etymology
The prefix Dispar is based off of the Romanian word dispărut, which means missing.