They straight up got rid of the chubby black girl from the first two seasons with the excuse that her family fled town. I wonder if it was actually a contract dispute or something.
You gotta remember that season 3 was filmed for YouTube Red. There were some characters from S1 that went missing from S2, like that girl Demetri was simping & ended up making out with in this season. The series is now backed by Netflix, so they should have more money to spend.