My Facebook user name was the name that I have used for over 20 years. My nickname was the name, is the name, that rings true for me. Everyone, including college professors used that name.
Facebook decided this was not me, not the name my family and friend have called me by for years and closed my account until I put my “legal” name. This name, which is NOT my legal name but is read as real by Facebook, became my identity. My friends began unfriending me because they didn’t know who I was. It took my six months to re-connect with people who never knew me as my “legal” name.