I'm not sure if this specific clip was posted of Laplus explaining why she's using Twitch for streaming and Youtube for pre-recorded content. There's some fodder for shorts meta/algorithm sperging.
Laplus and her manager think that if a Youtube channel does both shorts and livestreams, the shorts are de-ranked. This may be Youtube's attempt to nerf the shorts meta. But Laplus doesn't touch on that; to her, shorts views are an end to themselves, rather than a means to increase subs and livestream views. Why? Number go up, I guess. She's well aware that shorts don't get superchats, but (she says) she places a lower priority on Youtube earnings than number go up. She does say she feels pressured when livestreaming, and uploading shorts and videos allows her to produce content without that pressure.
In any case, she says that she won't necessarily split content this way forever, and she'll just do whatever she feels like.