1. Overuse and fatigue: Before becoming a singer, Charlene Choi used to be a voice actor, and her work required a long time to talk, which may lead to vocal cord fatigue.

2. Virus infection: Charlene Choi once revealed in Weibo that when she was recording a variety show, her body's immunity declined due to fatigue and she was infected with the virus. This may have caused her vocal cord infection.

3. Acid regurgitation: Charlene Choi once said in an interview that acid regurgitation is caused by overwork, which may cause damage to vocal cords.

In a word, there may be many reasons for vocal cord injury in Charlene Choi, including overuse and fatigue, viral infection and acid reflux.