No, you get refurbs as replacements at the Apple store and those receive a new case and a new battery.
Look at the reddit thread, there are even people with iPhones 7s reporting the same problem. Those devices are not much more than a year old max.
I don’t know if they are just making stuff up, but if the posts on reddit are true, than there are more people affected than just the ones with super old batteries.
As I said my iPhone 6s was replaced 13 month ago and is dramatically throttled according to Geekbench.