Where did you purchase it from?
My curiosity was piqued because the 2012 MBA I recently acquired has a battery where the back of the frame says it was made in 2016, but one of the cells has a different sticker hand-marked dated 2018. I think it was some sort of refurbished battery where they replaced the cells and recycled a genuine frame. It has clear wrapping on the cells.
It has fewer than 20 cycles on it, but only lasts a couple hours, due to age and the computer sitting unused for a few years.
Difficult to find a genuine, or OEM, battery now, and the aftermarket ones seem to be hit and miss.
I did find a place that purports to sell genuine batteries, amongst other NOS items, but their product photos conflict; on their site, it shows a genuine but old battery, and their eBay listings show what is clearly an aftermarket battery.
I've cleaned up the machine, and it now works as well as can be expected, but since it's more of a hobby/toy, not gonna throw much more money into it. Might take a chance on an aftermarket battery and call it a day.