That green is the only thing keeping her standing.
The Statue of Liberty's skin is copper barely 2.4mm thick, thinner than two stacked pennies. When it went up in 1886 it was the brown of a fresh penny. Oxygen and moisture hit the bare copper first and grew a thin red layer of cuprite underneath. Then New York did the rest. Coal smoke filled the air with sulfur dioxide, the harbor added chloride, and rain washed both onto the metal. The copper fed on the sulfur to build brochantite, the green copper-sulfate mineral that makes up most of what you see today.
That green crust seals the copper off from the air. Once it covered the surface, around 1906, the corrosion that created it slowed almost to a stop. Across a full century the skin has worn down by about five thousandths of an inch. When crews restored the statue for its 100th birthday, the copper body was one of the only parts they didn't replace. They rebuilt the torch and left the skin alone.
This is why the Park Service keeps refusing to polish it. Strip the green and you scrape off the protective layer and restart the whole reaction on bare metal that's already paper-thin.
The brown statue was the fragile one. The green one built its own armor.