It doesn't have 249g stamped on the part that sticks out of the drone. That's the easiest way.
Or, squint at the tiny writing on the label and find the capacity. The standard battery is 2xxx mAh, the extended 3xxx mAh. Don't remember the xxx digits, doesn't matter.
Depends on where you got it from and if you bought OEM or aftermarket? For example, you saw a really cheap aftermarket battery on AliEx and when it finally arrived, you could only squeeze out a few more minutes and you are concerned they simply sold you a plain unmarked standard battery.....