What is the difference between a suggestion and a slight?
It could be that our own insecurity, fear, or shame projected when advice is given. It can feel painful to be shown what would be better in the face of how we are not, even if such insight is a gift.
If you feel hurt, consider that it could be self-inflicted. While there are mean people in the world, we also tend to be wrong in attributing to malice what is so often just a misunderstanding. Give others the benefit of the doubt, and that includes giving it to yourself as well.