I also had a swollen battery in a 2013 Macbook Pro that was eligible for a free replacement in 2018 or 2019 (I forget exactly when, but it was before the 2019 1

I also had a swollen battery in a 2013 Macbook Pro that was eligible for a free replacement in 2018 or 2019 (I forget exactly when, but it was before the 2019 16" Macbooks came out). It was covered outside the normal warranty because of the swelling issue. Mine swelled to the point where the trackpad was slightly unreliable.