the.com/dog whistle

means A statement crafted so the general public hears something ordinary while a targeted subgroup hears a coded, often divisive, signal.

from Borrowed directly from the literal dog whistle, a device tuned to a frequency pitched above human hearing but perfectly audible to dogs. Political scientists and journalists picked up the image in the late 20th century — likely gaining traction through statistical and polling talk in the 1980s-90s — to describe messaging engineered to hit a frequency only certain listeners would register as meaningful, while sailing past everyone else as innocuous noise.