The link below from HokieKip is helpful.

He could have once before reclassified from 2019 to 2020 in an effort to gain more exposure, so this could be him going back to his original graduating class. OR, he could have been a 2020 graduate all along but has the HS credits to graduate in 2019 with a little summer school. Without knowing his history I don't know which situation applies to him.

There were kids I started with as a freshman in HS that graduated in 3 years, and we had one who "reclassified" to graduate in 5 in hopes of getting a b-ball scholarship. It didn't work out for him...