Don’t be alarmed by the video you saw. All electric cars discharge very fast when driven at speed. And a fast discharge also heats up the battery and motor, so to protect the hardware, the battery management system (BMS) cuts the power, which explains the 14% drop you noticed.
Because of aerodynamic drag, speed is the biggest enemy of range, and there is an exponential drop the faster you go. For example, if you drive at 160-170kph, the batteries will discharge 2.5 to 3 times faster than if you were driving at 90-100kph.
Even EVs with large batteries can lose charge at the rate of 1-2% per minute with hard and sustained high-speed driving.
So if all you want is performance and don’t care about range, the Mahindra XEV 9e in Race mode is very quick for short bursts of acceleration to overtake and fast highway runs. But no EV will give you full peak power indefinitely at extreme speeds.
It all depends on how the BMS is calibrated, but after sustained high-speed driving, expect a drop in power, which is normal for an EV and not a flaw of the 9e specifically.