Why some people are disappointed in the biopic ?

I learned that many fans were disappointed that the Jackson family was so involved in the film because they supposedly removed many important elements from Michael Jackson's life.

I would like people to explain it to me more thoroughly, because I'm kind of confused. Also, I'm asking for proof pls! I've been a fan of Michael Jackson, but I've been invested in his life a long time ago so I don't remember everything.

So, why was the biopic a bad representative one ?