The reason for the lawsuit between Long Jun and Peacock Company is that Peacock Company used Long Jun's works without authorization and obtained economic benefits from it, but failed to pay the corresponding copyright fees. This behavior may have infringed Long Jun's copyright, so Long Jun sued Peacock Company for infringement of his copyright and requested corresponding compensation.

Specifically, Long Jun is a famous male singer, songwriter and music producer in Mainland China. He has written tracks for many songs, one of which is "10,000 Reasons". This song was made into a ringtone by Peacock Company without the authorization of Long Jun, and the company obtained financial benefits without the consent of Long Jun.

According to the provisions of China's Copyright Law, copyright belongs to the author, and the author has the right to copy, distribute, rent, exhibit, perform, screen, broadcast, and disseminate information on his or her work through the Internet. Any use of the author's work without the author's permission may constitute infringement and requires corresponding legal liability.

Therefore, Long Jun’s action of suing Peacock Company may be to safeguard his copyright rights and require Peacock Company to bear corresponding legal responsibilities.