Is it possible there was/is a boy who was a part of the 2019 Grad year when he started school (maybe repeated 2nd grade - not due to grades or health) and is now in 2020.
And said boy is born after sept 1 2001.
If said boy was born after 9/1/01 then he would be age eligible for 2020. If said boy was born between 9/1/00 and 8/31/01 then he would be age eligible for 2019 but not 2020.
If he was born between 9/1/01 to 11/30/01, he is supposed to be in 2019.