>>30246617Clipwatcher here, but I'll take a shot at it.
Like most chubas, she started out a bit reserved and had some gimmick (being a tsundere) that she dropped pretty early on. She gradually got more comfortable and started acting crazier. She also adopted the nickname Haachama. Fans jokingly explained the difference in personality by asserting that Haato and Haachama were different people. Haachama took this and ran 1000 miles with it. She started releasing horror-themed lore videos about the multiple personalities sharing her body, and would put on an act of switch personalities mid-stream. Hope this helps.