The canary has been screaming its lungs out since Bill Clinton introduced his racist anti-immigrant bill in 1997, but both Republicans and Democrats have not only ignored its cries, but hastened its situation. Both parties have created this. Don’t think this won’t affect us all.
They used to bring canaries down to the coal mines because they were sensitive to methane gas. If you hit a pocket of methane gas, the canary dies before you do. So if you’re in a coal mine and see the canary is dead, it’s time to act (get the hell out) because if you don’t, the thing that’s affecting the canary will soon have the same effect you.
So in this case it would be saying “don’t be complacent about this thing is something only happening to immigrants (or people that “look like” immigrants), because it will soon be happening to you too if you don’t act on it.”