probably 1000mAh real capacity
Gemini says this:
The practical max capacity for a genuine 18650 battery is 3500mAh to 3600mAh. Any cells claiming capacities significantly above this (such as 4000mAh, 5000mAh, or 9800mAh) are fake, overrated, or dangerously fraudulent. [1, 2, 3]
Genuine...