AA incorrectly identifying RSpec differences

Hello. This has been bugging me becasue I’ve been trying to figure it out for days, but I’m assuming it must just be an incorrect notification on App Academy. From the specs below, it says they should pass (and it is correct), but that using a subject instead of let would allow us to persist the subject state; however, this is not the case. Subject and let are nearly synonymous in this case – neither would persist state past the it block. Wanted to give feedback/heads up. If I’m incorrect, though, apologies and could somebody explain?

class Dog
  attr_accessor :name

  def initialize(name)
    @name = name
  end
end

describe Dog do
  let(:dog) { Dog.new("Bear") }

  describe "name property" do
    it "allows us to manipulate name" do
      dog.name = "Rocky"
      expect(dog.name).to eq("Rocky")
    end

    it "allows us to read the name" do
      expect(dog.name).to eq("Rocky")
    end
  end
end