The white sash was added to cover the offensive mer-titty. Here's a news story that plays up the irony that Warsaw's actual mermaid symbol is fully bare-breasted (as can be seen here, in a nice article that also explains why Warsaw's symbol is a mermaid).
But what I find more ironic is everyone is worried about a bare breast when the mermaid's scales start dangerously low on her hips, so low you can almost see her minge. Who's going to protect us from that, huh?