Why does the user name display special symbols when logging in?

When logging in, the user name is displayed with special symbols. According to relevant information, the display of special symbols is for personal use, and some user names have a specified format, which can be without spaces, underscores and numbers at the beginning. Bika is a cartoon application community for reading cartoons on mobile phones, which contains a large number of fine cartoons and has brand-new functions of searching, collecting and scoring. Bika Bika features a search function, supports simple and complicated text search and search functions, and can also collect comics.