The theory is most of the jannies left after the recent hack and doxxing so Partap hired a bunch of jeets to replace them. Its also very likely that many, many, many jeets flooded 4chan after the hack. They'd been infecting the boards since 2016 and it got so bad they had to get rid of the dedicate board for pajeets. That only made them more annoying.
/biz had become, and still is, mostly jeets peddling scamcoins. /pol is still a festering shithole, heavily jeeted with a couple dedicated jeets making sure the private Indian chat rooms stay coordinated on attacking anything they don't approve of.
Very few humans left on 4chan. Its mostly jeets and Partap playing with himself.