Question about throttle percentage change in hovering flights

Why does the throttle percentage level on the instrument panel go up as the battery goes down over time on a hover flight?

Drone hovering is basically the same level of consumption current, but if throttle percentage goes up, does it mean that consumption current increases? Then shouldn’t we go up, not hovering?

Or does it mean that the PWM signal level for ESC control has increased? The fact that the PWM signal level is high will eventually lead to a higher motor rotation RPM, which is also not hovering
What is the throttle percentage value calculated from?

Generally speaking, if you’re just running out of battery and you need to increase the output a little more, if you increase the output, it’ll be an upward flight, not a hovering flight

Can someone explain this clearly?

As the battery is drained, its voltage gets lower. In order to achieve the same amount of thrust, more “throttle” and therefore current is required, and that’s achieved by a higher PWM signal from the autopilot which is trying to control the altitude.

Does that make sense?