How long does the gate charge of the MOSFET transistor last?

The IRF630 transistor's datasheet lists a gate-to-source capacitance of approximately 700 pF. However, this capacitance is specified for a frequency of 1 MHz and a drain-to-source voltage of 25 V. I measured the capacitance of this junction and found it to be 2260 pF.

I charged this capacitance with 7.6 volts and left the transistor for an hour. Then, I measured the gate voltage with an oscilloscope, and it was 6.8 volts. Over the course of an hour, the gate voltage dropped by 0.8 volts. Just don't measure the gate voltage with a voltmeter, you likely won't see anything, as the input impedance of the voltmeter and oscilloscope is too low and sufficient to quickly discharge the gate capacitance. An oscilloscope can measure the voltage in trigger mode.

Therefore, it's important to discharge this capacitance while the transistor is operating, which is what gate drivers do.

I also charged a 2200pF capacitor with a voltage of 7.6V and left it for 20 minutes. As you can see, the voltage across it was 6.7V and it discharged by 0.9V.