Here’s how to recalibrate your MacBook’s battery: Fully charge your MacBook to 100%. Keep the laptop running while connected to the power supply for a couple of hours. Unplug the MacBook from
macbook air 2015 battery capacity

The cycle count is only 29 till now but battery capacity is already down at 98%. My old MacBook Air (2017 Model) was really up to the mark for first two years at least, but M1 somehow feels like its is degrading fast (in terms of battery health compared to usage). They also suggested the following for M1: - Not charging the Mac to 100%.

If you are running an older version of macOS and the condition is "Service Battery", then that means macOS has detected a hardware fault with the battery and you should have Apple replace the battery (macOS 10.6-10.14, perhaps even 10.15). Otherwise "Replace Soon" or "Replace Now" indicates the battery capacity has dropped below 80% of Design

MacBook Air 13", Early 2015 macOS Monterey 12.4 (21F79) I recently got the battery replaced. I am observing a difference in charging status depending on where I look. I never bothered to check these with the previous battery. When the light on Magsafe power adapter goes from amber to green, the battery status on the Menu Bar says 100% charged. I changed the battery in my old Macbook Air 11" (mid 2013). It all appears to work fine after installation. To recalibrate the power system, I followed the steps outlined by, e.g., ifixit: With the computer turned off, I let the battery charge until the connector went green, and two hours more.
For best performance, replace your battery when you reach its maximum cycle count." Where maximum cycle count for macbook air m1 shows 1000. Current state of my m1's battery is "maximum capacity 87%" and "cycle count 192". That perhaps says maximum capacity will reach to 80% where cycle count will remain way lesser than maximum (i.e, 1,000).
1Fj9Ok. 145 358 40 197 249 351 56 414 84

macbook air 2015 battery capacity