Yes and no. Yes I think some people may have thought Justin Bieber’s music was “teenybopish” in the beginning, but then he did start singing on YouTube when he was sixteen. It’s natural to believe that his music would mature as he matured.
I think people will listen to his newer music and decide whether they like it or not by the way it sounds now. It they like the lyrics and the melodies, they will listen to it. If they hear it and don’t like it, they won’t listen to it. What his sound was like in the past won’t, and shouldn’t, make that much of a difference.