Falsely accused. The woman in question has stated that the charges, which were brought by a 3rd party btw, were an act of homophobia and that Heard never assaulted her.
Also, Depp has a questionable history too. Many of his exes has spoken of him in Dr Jekyll/Mr Hyde like terms, twinning, love bombing, etc. He jumps.fro. relationship to relationship with little down time between, has dates minors and seems to prefer young women, and women who are emotionally vulnerable due to rebounding or other insecurities. There have been witness reports and rumors of violence. He was possibly involved in a murder. There was an incident involving Kate Moss being injured on a staircase and another incident of a hotel room being demolished. He has cheated on multiple partners and there has long been talk about his jealousy and the problems it causes.