If you get arrested for sex offences, you have to fly one of these flags on your house, so people know to stay away.
If an area has a large amount of sex offenders, they also have to add additional "paedo flags" to nearby lampposts etc as a warning to people travelling near the area.
I think they're likely just shredded because of the recent weather, and there's no additional symbolism there.
There's a small chance I might be incorrect, of course.