"Red banner" is a phrase that usually symbolizes a sign of recognition, achievement, or prominence. It is often used to describe a flag or banner that is colored red. Full definition
Design illustrates a dark red banner on a vintage style burlywood - color background. (showeet.com)
It involved the conversion of an old bathhouse into a club — Starck kept the tiles, put Soviet slogans on the walls and hung red banners around the place. (newscientist.com)
LOTS of impact from that big red banner recently. (justarsenal.com)