>>7084153That clip is from 2019/07, 9 months before she officially started calling herself Haachama (i.e. changing her greeting). Judging by Haachama's reaction to Matsuri in the clip above (2020/06), she was for some reason surprised at her reluctance.
I'm guessing either Haachama changed her mind on what she said, or she just simply forgot she said that in the collab? Still doesn't explain why she told Matsuri (and her only?) to not call her Haachama in the first place though. Is it because she had no plan on making Haachama as integral to her character as it is now and felt that Haato-chan was more personal than Haachama? At least this reinforces that they were really close at one point.
Also for
>>7084742:
Maybe Haato and Haachama are actually different personalities for real 