The warranty period of DJI Batteries are 200 cycles or 12 months (whichever comes first).
But the real life expectancy really depends on how you use the battery.
If you don't discharge it lower than 25% regularly, store the battery for longer than 48 hours only at storage voltage (3.8V per cell, or approximately 40% charge), and don't fly much in sport mode, expect about 200 - 400 cycles, maybe a little more.
I have my DJI
Mavic Air 2 for 8 months already, I own the Fly-More combo (3 batteries), after 8 months of flying, all batteries are at around 100 cycles, all of them still work perfectly fine, and flight time difference is almost not noticeable (maybe 30 seconds less or so). I try to care much about my batteries, only store them at storage voltage, charge them only when I know that I will fly in the next 3 days, and don't fly them lower than 20% regularly.
You can use
Airdata UAV to sync your logs and check the battery status, the flight time, cell derivation, graphs, and much more with free and premium accounts.