That graph is the result of measuring some motors parameters with the motor on a dynamometer. The V5 motor’s internal firmware is limiting current, and therefore torque, so it is a little different from the type of curves you may find on the internet for DC motors. You can see more typical curves (theoretical) for the older 393 motor that was used with the previous control system here.
The motor would generally be commanded to run at maximum voltage, then the load on the motor is increased while parameters are measured. As load is increased the motor current increases until firmware limits it at 2.5A. Maximum motor output power is at around 75% of max rpm, that doesn’t mean you should command the motor at 75% for max power, it means don’t have a load on the motor that causes the speed to drop too much below that value.