People use red screen for:
Because I have blue LED lights on and it matches perfectly making my face or a part of my face red and leaving the blue lights behind me. I liked the red screen tbh, it's cool to make tiktoks or like photos and edit them to make them look professional.
For colorcast correction when using Google Meets.
Not hard on the eyes, especially when coming out of a dark area
To read a book with less blue light.
it helps fix a projectors keystone
To prank my friends and say I have L.E.D's.