I mean, a lot of vtuber fans and vtubers themselves are into underage anime characters. We can try to skirt around it, but that's just how it is. The most subscribed to vtuber on Youtube is a loli - people can try to say otherwise about Gura, but lets be real, we all know she's designed as a loli and intentionally puts on a bit of loli act. And one of the biggest stars of vtubing last year was Kobo who is basically the ID version of that. Openly lolicon or shotacon vtubers maybe aren't as common but they're still around - Kenmochi, Utako, and Zaion from Niji all come to mind. There's a good chance that if the vtuber you watch is joking about loli or shota stuff it's because they're into it, at least to some degree.However, I do not understand the pedophilia stuff with vtubers. Fubuki and Noel and whoever else in hololive talking about lolis and shotas. Rie talking about little kids.
Is it supposed to be funny? Is it supposed to be skirting the edge of a taboo?
Beyond that, I do think the "taboo" stuff is a part of it. I know Zaion does the whole "oh hahah I'm kind of a shotacon but its alright guys don't cancel me" stuff (not a direct quote) and I've heard others kinda do it to. The idea that what they are saying could get them in trouble but "hey, you're cool, right, chat?" and whatnot.