Why does Clash of Clans display illegal names?

Account name appears: illegal characters and special symbols will appear in illegal names.

Reasons for illegal names:

Player names include sensitive words, leader names, homophonic words to curse officials, vertical names, negative social energy, pornography, violence, duplicate names , rare characters that cannot be recognized by the system, obvious curses and vulgar words, including parents, death and other words that are obviously insulting to others. These names will be punished and forced to be changed.