It's literally classic Cover behavior I don't know why anyone is surprised. When they have vtubers that aren't the highest performers they let encourage their talents to collab with everyone and anyone they could leech some numbers off see holostars and holostars en. When their talents are doing the best they close off collabs and try to keep them to a minimum see HoloJP more or less completely stopping collabs with NijiJP when they became more popular and HoloEN rarely collabing outside HoloEN. Corporate level leeching.