So I was watching this:
https://youtu.be/NLO5-IyS5pEAnd there are some interesting takeaways for vtubing. First he says that his most profitable video by far is his 3 hour livestream VOD. This is because of how Youtube Premium divvies up the cost among the videos you watch most. The algorithm particularly likes livestream VODs for deciding who gets a cut of the premium money. For most Youtube creators this is irrelevant he says not many people do live streaming on Youtube but obviously Vtubers are one of if not the biggest groups streaming on Youtube meaning they're probably getting a huge disproportionate amount of Youtube Premium money based on people watching their Livestream VODs. This guy was talking about his single Livestream with 1.6 million views so you can imagine how much they average Hololive member must be making with 20 million channel views a month,
Conclusion is that to support your favorite Vtubers the most cost effective way might be to get Youtube Premium since the way it works is hugely advantageous for vtubers.