What does it mean to describe people as red?

Sister Hong means a fan of stars and a big fan of rice circles. The fan circle is made up of idolized fans, and each fan has several big fans who can call on other fans' abilities. These big fans have many fans. No matter what you send, you regard it as a traffic star, and many people forward it. In terms of idolization, most of them are girls, and Dafen is basically a female powder. They also bring their own traffic, and some netizens call these big fans "red sisters". One-stop study abroad strategy in ing.com