Stanley Adventure Switchback Thermos Mug Rusted

I bought the Stanley Adventure Switchback Thermos Mug 0.47-liter version on November 23, 2023. Even though it's only been five months, the product, which claims to have a stainless steel construction, has already started showing signs of rust and corrosion on the inside. I must say, I am quite disappointed with the performance of this product, especially considering Stanley's reputation for producing high-quality items. Despite being made from 18/8 stainless steel and BPA-free materials, and boasting claims of being unbreakable, rustproof, and incredibly durable, it has not lived up to expectations. I had high expectations for Stanley's reputation for quality when I made this purchase, but unfortunately, the thermos has been a disappointment. I would like to request a refund and a replacement with a new product.