Thank you for your answer.
The configTICK_RATE_HZ is still 1000 though,
Because configSYSTICK_CLOCK_HZ changes when the SystemClock is changed,
if the Clock is changed during operation,
vPortSetupTimerInterrupt() by myself to update the FreeRTOS SysTick.
If we update it with vPortSetupTimerInterrupt() when we change the Clock,
I was able to confirm that the FreeRTOS SysTick works in sync with the changed Clock.
Very helpful.
Thank you very much.
I appreciate it very much.