"Protest banners" refers to signs made of fabric or paper that people carry during public demonstrations or protests to express their opinions, demands, or opposition to a cause or issue. Full definition
It was his name that appeared on protest banners when teachers went on strike. (bbc.co.uk)
He'd already seen small amounts of protest banners at games in the 2015/16 season and was well aware the fans were not happy with his lack of activity in the transfer market. (justarsenal.com)
The clerics have also said they will display protest banners in the city of Aigion, which is the largest in the diocese. (premierchristianity.com)