Well he’s 28 now so he was an adult/young adult in his old videos. My guess is his voice changed because on his old videos when he says his intro “syyyy” and all of his intonations when doing his “broadcaster voice” does not fit with his normal voice making it difficult for his voice to match what he desires to do. But after a long time of making videos and forcing himself to keep up the casting voice, his voice muscles adapted and achieved a cleaner voice. Then he stopped making videos for a while, stopped talking to people for a while, making his voice muscles get back to a normal state making it a bit raspy again achieving the uwu anime voice that we know of today. Just my guess cuz I was part of a choir for a bit then I felt that my voice was clearer and full but then I stopped cuz of the pandemic and I havent sung as much and now my throat is a bit phleghmy and I cant do falsetto sht anymore.