My X-Trail e-Power shows a fuel consumption of 6.9 in the city. But when I drive on the highway at around 120-150 km/h, the fuel consumption increases to 7.1. Is it due to my driving habits? Can any expert advise on this?

Electric cars are like this, indeed. The motor consumes much more energy at high speeds, while low speeds are more energy-efficient, which is the opposite of fuel-powered cars. The X-Trail EP relies entirely on electric drive with the engine generating electricity, so it consumes more fuel at high speeds.

At a speed of 100 km/h, my fuel consumption is a bit over 5 liters. At 120 km/h, it's over 6 liters.

Only 7 liters for 120-150 km? Really? Even lower than a sedan?

At a speed of 110 on the highway, the fuel consumption is just around 5 liters. [666][666] When driving at speeds between 120 to 150, most 4WD SUVs have a fuel consumption reaching around 10 liters. [Rose][Rose]

Yes, it's quite normal for there to be increased wind resistance at high speeds.