Oozora Subaru is a member of Hololive 2nd Generation.
Subaru is known for making a raspy whispering voice when doing ASMR, which convinced her viewers that she was impersonating Donald Duck. This joke was revisited when she made a joke appearance in 3D with Roboco as a duck wearing her signature baseball cap. Since then she has been associated with being a duck.
Her duck was featured in an animation made by @KS_wktk dancing next to Subaru (in human form). YouTuber Rul3r of Wind used this in a video, then YouTuber KaasToast posted a cropped video consisting of only the duck.
Later, u/PrimaryResearcher870 used the duck in a meme posted to /r/dankmemes. This went viral outside of the Hololive community, leading to questions asking about the origin of the duck and why commenters kept saying “shuba shuba”, one of her catchphrases.
When Subaru noticed that people did not know the dancing duck meme was related to her, she made a “press conference” video claiming that she was the duck. She was saddened that she (her human form) was cropped out of the animation and expressed her wish for people to acknowledge her and subscribe to her channel (and to be re-inserted into the meme).