Bayer Leverkusen is seen in Germany as a plastic club by a lot of fans, mostly because they have distanced themselves from their working class roots. They have a family friendly atmosphere and stadium. As a result a part of the ultra fanbase is trying to distance themselves from that clean image by being edgy and coming up with shocking statements.
They have a cult mascot, “der Zitronenmann”, they use as a “spokesperson to” say controversial shit trying to get attention and stay relevant. They have provoked and picked fights with rivals as well, mainly Bremen and Koln.
Leverkusen sees Bremen as rivals, rivalries arent necessarily a two way street. That is why they tried to start shit though, to make it more heated and serious. When they did it with Koln they got chased around the city. Their Ultras are a bunch of useless cunts, they also caused problems in Portugal. Not by fighting with opposing fans, but by harassing locals and businesses.