Genuinely thought this was solopipb''s moth girl for a second.
It technically is, in the sense of being a moth girl by solopipb. If you follow the link to her twitter, he/she is credited as character designer (presumably; the precise phrase used is "馬麻:ソロピップB". 馬麻 is meaningless in Japanese but appears to be a Chinese transliteration of "Mama", and vtubers referring to their designers as Mama, Papa or similar is common.)