Printing hangs when toggling pin (no replies)

Hello all,

I made my own gcode to toggle the LED lighting of my printer.
I am working with Marlin V2.0 (newest).
I added the new gcode (777) function to gcode/gcode.cpp (inside the switch case of "GcodeSuite::process_parsed_command") and also to gcode/gcode.h to the class "GcodeSuite".
For the actual code I added a new file called 777.cpp with the following content:

#include "../../inc/MarlinConfig.h"
#include "../gcode.h"
#include "../../MarlinCore.h"

/**
 * M777: Switch printer lighting on/off
 *
 *  P(pin)      - Pin number
 *  T(bool)     - Toggl lighting on/off
 *  S(state)    - Switch lighting on if 1 and off if 0
 */
void GcodeSuite::M777()
{

  const int pin_index = PARSED_PIN_INDEX ('P', GET_PIN_MAP_INDEX (LED_PIN));
  //SERIAL_ECHO_MSG("pin_index: ", pin_index);
  if (pin_index < 0) return;

  const pin_t pin = GET_PIN_MAP_PIN(pin_index);

  if(parser.seenval('S'))
  {
    const byte status = parser.value_byte();

    if(status == 1)
    {
     pinMode(pin, OUTPUT);
     extDigitalWrite(pin, 1);
    }else if(status == 0)
    {
     pinMode(pin, OUTPUT);
     extDigitalWrite(pin, 0);
    }else
    {
     return;
    }
  }

  if(parser.seenval('T'))
  {
    pinMode(pin, OUTPUT);
    extDigitalWrite(pin, !extDigitalRead(pin));
  }
}

This is working fine, but when I am printing an then toggle the LEDs the printing pauses for about 2s and continues then. This only happens when switching off (S=0)... This happens with the T command and the S command.
To send the gcode and control the printer I use a MKS TFT32 V3.0. My Mainboard is Bigtreetech SKR V1.3.

Does anyone have an idea what can cause this behaviour?
Or does anyone knw where to post that? (Github as bug?)

Thank you in advance