children may use a badge or other visual cue to let candy-givers know that they may communicate differently.

But here’s the key point:

You should not assume that every child carrying a blue bucket is autistic.

The child may simply like the color.

They may have chosen a blue bucket because that’s what they had.

The bucket may have been purchased specifically because it was available.

Or their family may indeed be using the color as an informal awareness signal.

There isn’t a universal rule that says “blue bucket = autism.”