This is actually in the New York raid. There's a couple flappies around, but to me this sign looks like it's got scorch marks as well. Maybe I'm overthinking it, and again, I think they didn't expect people to actually stand around and stare in this part of the zone

Iirc, this is Tokyo. There's big giant birds. One could have simply hit it, Take a bite out of it. or simply hit it was something that eroded the sign. There's lots of ways this could have happened where there'd be no debris from anything else.