>>19429984They're extremely busy with recording sessions for songs, promotional events, live, concerts, radio shows and other things like Hololive Alternative / Error / other unannounced projects.
And with time, they're progressively getting more and more busy as Hololive grows in size and popularity all over the world.
On top of that, they have to stream and talk for hours almost everyday since it's their main content.
So it's not really a surprise that at some point, their throats just can't keep up.
There's also the fact that their voice is literally their lifeline for their entire careers, if someone's throat starts to hurt then it's a real serious issue.
They need to be extra careful about that.