The JETson Nano IO port is set to the input state, and the level is abnormal

HI,
I use the 26 and 18 pin external keys on the Jetson nano and connected with a pull-up resistor. When the key is pressed, the level can be measured to 0V. When the key is released, it is 3.3V. But when I set pins 26 and 18 to input mode and run the program. When I pressed the key, the level was still 0V, but after releasing the key, the level was only 0.8V. After a long time, the level could not recover to 3.3V when the program was not running. However, when the program is stopped, the IO port level is restored to 3.3V. As long as the program is not run, the level when the key is pressed and released is normal, but when the program is run, the high level is only 0.8V when the key is pressed and released. What is the reason?

The program I run is downloaded using the following instructions. The program name is simple_ input. py

The download instruction is: git clone GitHub - NVIDIA/jetson-gpio: A Python library that enables the use of Jetson's GPIOs