Why would you not be your authentic self? What is so intense? Trying to understand INFJ

Hi so lately I have been seeing a lot of posts about people claiming that when INFJ drop the people pleasing tendencies and stop trying to adapt to everyone, to become their authentic self. Then people are surprised or friendships lost. Why is that?

Why would you not be your authentic self from the start? I get that if someone I am friends with suddenly start being different that is not what I was expecting. Then how can I get to know the real person if you are not being yourself from the start? Some INFJ have stated that people are surprised by the intensely and that they no longer stay friends after because they cant benefit from INFJ giving nature.

What exactly is intense about INFJ?