What happened to my Macbook Air's battery?
Third-party batteries are a bit of a lottery. There's no telling how closely the specification and quality matches Apple's own parts (which they do not sell on).
The cycle count is a guide to the life of the battery, but that's all. A four-year-old battery is still a four-year-old battery.
You can take it to Apple and get a proper Apple part fitted. It will cost 'some money', but of course part of that is getting a quality product, which will be under guarantee to work properly.
The alternative would be for you to replace it yourself. You can get 'genuine' Apple batteries on eBay and other websites: though as said, Apple don't sell spare parts on the open market, so these are either 'run-ons' from the factory that Apple uses, (or units that didn't meet Quality checks); or they are counterfeit. So again, a bit of a lottery. Or choose a third-party supplier that you feel to be trustworthy, with a reputation for Apple peripherals and parts, rather than someone just trying to cash in on demand.