I have no idea if there are systems on a submarine that might experience extreme temperatures. But for the hull, since it is constantly surrounded by liquid wat

I have no idea if there are systems on a submarine that might experience extreme temperatures. But for the hull, since it is constantly surrounded by liquid water, I would expect that it does not regularly experience temperatures less than ~0C. Maybe there's a concern when surfacing in the arctic? That said she obviously shouldn't have faked data whether it was stupid or not.