The value about STM32G431 PWM Capture demo is incorrect when the frequency is below 3kHz

Hello, I study the stm32 TSP recently. I find that the demo advanced_pwm_configuration about the stm32G431 PWM Capture has some problem. The value of PWM Capture is incorrect when the given frequency is below 3kHz. Why does this situation occur? I know that the G431 is not contain HRTIM, So If I want to recognize the frequency from 1 Hz to 10kHz, what should I do?