Why can't the watchdog be used on Arduino nano 33 ble

#include <mbed.h>
mbed::Watchdog &watchdog = mbed::Watchdog::get_instance();
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, HIGH);
delay(1000);
digitalWrite(LED_BUILTIN, LOW);
watchdog.start(1000);
}
void loop() {}

The above code can be used in Arduino nano RP2040, but it cannot be used in Arduino nano 33 ble

I suggest you post that question here: Issues · arduino/ArduinoCore-mbed · GitHub