Unless a child has the grace to grant a parent forgiveness for their (forgivable) failures, and unless a parent was able to create a safe and loving environment in which a child could grow up with such a mindset, estrangement is inevitable.
Usually, the crux which this revolves around is the realization that each child is a unique person with their own potential, and hopes, and dreams, and that it is not fair to the child if the parent does not make providing the best possible environment for that child a central focus of their life.
Many people who are (rightly or not) disappointed by their parents and troubled by aspects of how they were raised will view this as something private and will only open up in therapy, or some other private interaction --- some folks consider the anonymity of online intercourse to have a privacy of/distance from their real life that it is safe to mention things --- I guess in my day it was the "bartender effect".
Consider your question as coming from a position of grace/luck and count your blessings.