Sensor in plumbing vent stack?

So I googled my little heart out and I can’t find what this wire or sensor is so would somebody please put me out of my misery?

I assume its not just a wire to hold bees nests?? Maybe it is since I can’t say what else it is.

Thanks,

Is that cable line?

Looks like a radio antenna maybe…just not the best mounting method.

Could be a heat cable

VHF antenna hidden from the homeowners association.

Ive never seen one but I’ve heard of heating devices for plumbing stacks. The condensation can freeze at the top of the stack if it gets cold enough (this I’ve seen) and can restrict air flow. Just an opinion.